Penn’s Slammer IV Review: The King of Saltwater Spinning Reels

Reviewed by: Pete Danylewycz
Last Updated:

Penn Slammer IV Review

Penn Slammer IV Review

In our final analysis, Penn’s Slammer IV is an amazing saltwater reel that you won’t regret adding to your arsenal. Once you break in your new Slammer IV, it's going to be very, very smooth. Give it a bit of use before you judge, and let those gears settle into one another.

USAngler Rating: 

As an experienced angler and long time product reviewer for USAngler, I recently got hands-on with the Penn Slammer IV and was thoroughly impressed. This reel maintains the robust aluminum body of its predecessor, the Slammer III, ensuring exceptional rigidity. Its HT-100 and Dura Drag systems, particularly in the 2500 sizes, are as reliable as ever. The Slammer IV's heft is a testament to its quality, with Penn choosing brass for standard gears and stainless steel for the DX upgrade, eschewing cheaper materials.

In performance comparisons, the Slammer IV outpaces its Shimano counterparts significantly in terms of retrieval speed. For instance, the Slammer IV 2500 standard model achieves 33 inches per turn, while its HS variant goes up to 39 inches, easily surpassing the Shimano Stradic 2500's 30.7 inches and even its high-speed version's 35 inches. Similarly, in the larger models, the Slammer IV consistently shows a 6-inch advantage in retrieval per turn over equivalent Shimano reels.

Another standout feature is the Slammer IV's massive spool, offering remarkable line capacity that virtually eliminates the worry of getting spooled. As an angler who values durability and performance, the Penn Slammer IV is a reel that genuinely stands out in its class.


  • Rigid all-metal body
  • Unmatched drag performance from the HT-100 and Dura-Drag
  • Strong, CNC-machined brass or optional stainless gears
  • Very fast retrieval rates
  • Huge line capacity


  • Heavy for size
  • Not as smooth starting and cranking as Shimano

Analysis and Results

Penn Slammer IV

What’s the difference between the Slammer III and Slammer IV?

The Slammer III debuted to much fanfare, winning the coveted iCast 2016 award for Best Saltwater Reel. It quickly won the hearts of inshore and offshore anglers for its run-stopping power, amazing drag systems, massive capacity, and rugged durability.

In 2021, Penn released the Slammer IV, adding the much-requested 2500 size to the line-up, boosting drag performance at the low end of its settings, adding a hydrophobic line roller, and improving the sealing and performance of the bearings.

The result is a true upgrade to the Slammer III.

Models & Specs

Penn Slammer IV models


When you tie into a big fish, all the stress and weight of that fight is translated directly to your reel, creating enormous forces on its gears and guts. 

Those forces are trying to warp the body of your reel, allowing the gears to change their alignment. If the body flexes, tooth position will shift, leading to potentially catastrophic failure in precision-cut gears.

Plastic and carbon fiber can only provide so much stiffness; all-metal bodies are where it’s at for big fish.

Penn’s Slammer IV uses the same time-tested aluminum bodies of the Slammer III, providing unmatched rigidity.


Penn’s drag systems, the HT-100 (in the 2500 sizes) and the Dura Drag are legendary.

I don’t say that lightly.

The HT-100 was named for its testing procedure, during which 100 miles of line were run through a test reel with the drag engaged. No wear was evident at the end, nor was performance compromised in the least.

The carbon fiber drag washers that provide the HT-100 with world-class performance create smooth, consistent, reliable pressure at all settings, and it’s the perfect pairing for the 2500-size body, gearing, and capacity.

The addition of a 2500-size reel to the Slammer IV lineup was a smart move for Penn, as inshore anglers have been drooling over this possibility as though it were the promise of a perfectly-grilled porterhouse. Ideal for reds, specks, snook, and other inshore gamefish where larger reels are just not necessary, the 2500 Slammer IV, armed with the HT-100, is just about perfect.

All of the larger sizes in the Slammer IV family use a redesigned Dura-Drag system that’s been improved by adding a bearing to increase smoothness. The result is that hesitation is unnoticeable, even when you’ve got your drag set tight.

The Dura-Drag was originally the heart of Penn’s International before being introduced to the Slammer series. To say that it has won the hearts of anglers in the salt is something of an understatement. 

It’s quite simply the best drag system offered on any spinning reel at any price.

The combination of proprietary materials and careful design yields a drag system that can endure anything you can throw at it in the fight of a lifetime, and it dissipates heat, providing smooth, reliable tension even after hours of battling big fish.

Penn ran the Dura-Drag through 30 hours of continuous punishment without any performance loss. 

You can trust this drag system to help you win the fights of your life.

Each size of the Slammer IV comes with an appropriate drag maximum, allowing you to run heavy line with confidence.


The Penn Slammer IV DX swaps brass for stainless steel.

Penn skips the cheap plastic or lightweight aluminum, offering their standard gears in brass and the upgraded DX option of stainless steel.

And while both brass and steel are heavier than the alternative, they’re also more durable, eliminating the possibility of fight-ending deformation or tooth loss.

Penn’s CNC-machined brass gears are incredibly robust.

The CNC-machined brass or stainless gears feature teeth that come together perfectly, creating a solid feel that’s reassuringly grounded and “tightly smooth.” 

You can really feel the difference between the Slammer IV and its rivals from Shimano.

Yes, the Slammer IV isn’t as smooth out of the box as the Shimano Saragosa or Stradic, but give the Penn some time to break in - and it will break in as you use it - and it’ll become very smooth indeed. And while it may never rival the slickness of these Shimanos, between the amazing Dura-Drag and the durability of those tough brass or stainless gears, I know which reel I’d want with a 150-pound fish on the other end of my line.

Each size comes with appropriate gear ratios for its intended uses, with the addition of High Speed (HS) models in the 2500, 4500, 6500, and 8500.

These increase retrieval rates substantially.

In the 2500, for instance, the standard reel picks up 33 inches per turn, while the HS gobbles 39. The 6500, when compared to the 6500HS shows the same 6-inch increase, jumping from 42 inches per turn to 48.

By contrast, the Shimano Stradic 2500 grabs just 30.7, and even in its high speed variant, it manages only 35 inches or retrieve. Shimano’s Saragosa 6000 picks up just 41 inches per turn, and it’s clear that apples-to-apples comparisons put the Penn Slammer IV far ahead in terms of speed.

That matters, as any angler who’s had a big fish run straight at them can attest, and keeping a tight line when that happens is the difference between reaching for a landing net or gaff or feeling heart-sinking frustration.

Spool capacity

Penn Slammer IV Spool Capacity

Penn’s Slammer IV runs the same spools as the Slammer III, meaning that they deliver massive capacity.

There is nothing worse than watching your spool empty as a big fish takes your line for a run, and getting spooled is always game over.

The Slammer IV isn’t going to let that happen, and huge spools have your back when you need to let a marlin or sailfish take off with your lure.

These spools just offer ridiculous numbers, holding 805 yards of 50-pound braid on the 10500, or 440 yards of 50-pound braid on the 7500!


Ideally, you’d be able to dunk your reel, crank it a few times, and never see saltwater penetrate into its guts.

That’s not possible with the Penn Slammer IV.

The Dura-Drag is well-sealed, and Penn has added more gaskets to the Slammer IV than were present on the Slammer III.

But it still earns an IPX6 rating, meaning that anything short of immersion should keep the insides dry.

That matters more than you might think, as reels get hit with spray all the time, not to mention routine rinsing in freshwater after a trip.


Brass and steel aren’t light materials, and big gears, huge spools, and rigid all-aluminum bodies aren’t weight-saving choices.

It’s clear that the engineers and designers at Penn chose strength and performance over weight savings, and Penn’s Slammer IV lineup is built more like a linebacker than a ballerina.

Penn has managed to shave an ounce here and there off the Slammer III, but if lightweight is what you’re looking for, look elsewhere.

About The Author
Pete Danylewycz
Born and raised in Cleveland, Ohio, Pete grew up fishing on the Great Lakes. Whether he's casting a line in a quiet freshwater stream or battling a monster bass, fishing is his true passion.
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