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Home » Men's SIM Pro II Buoyancy Shorts

Updated Construction

Yamamoto SCS Coated Stretch Knit - Easier to Get Solid, Snug Fit - Seals Out Water Better

Showing seal that keeps water out

Optimized Fit

Optimized Length and Leg Openings - Higher Rise in Back - More Comfortable Front

Showing the new fit on a swimmer

Updated Graphics

Added Color Hit to Back Waistband for Improved Technique Evaluation From the Pool Deck

Color added for visibility and evaluation

Train Like You Race® With the SIM Pro II

The SIM is the first practical triathlon and swim training tool to mimic the body position and experience of a wetsuit swim by lifting you up — without overheating from wearing a wetsuit in an 80°F pool. This patent-pending suit is a game changer. It's better than a pull buoy, because it lets you kick and turn naturally. It's also gives just a touch of warmth for those cold morning workouts. The SIM makes every swim a race-specific training workout. Once you try it, you won't ever want to go back. Note, these shorts are designed for the pool and should have excellent durability if you rinse them after use with fresh water and dry them thoroughly.


Fit tip: SIM Shorts are neoprene and will loosen slightly in the water. However, they do have a drawcord for adjustment.


Get the Fastest Body Position

The SIM Pro lifts up your hips just like a wetsuit, putting you in the fastest position possible and helping your body develop the muscle memory you need on race day. Most top wetsuit manufacturers focus on buoyancy alone.  Sure, wetsuits help lift you up, but that's not enough – and in some cases it can really get in the way of fast swimming. To get the fastest body position, you have to remove buoyancy, mass and resistance from the places you don't want it. With the SIM Pro, we add buoyancy to the hips and legs, creating the fastest position possible.  We also use Yamamoto's SCS coating to further reduce form drag.  We're confident you'll feel the ROKA difference as soon as you jump in the water.

Improve Your Technique

If you want to swim faster with less effort, then rotation matters a LOT.  A fast freestyle requires effective rotation along your centerline to generate power and speed in the most propulsive phase of your stroke.  The Maverick Pro leverages basic laws of physics.  We call our application of those laws "RS2" - the ROKA Speed Stripes.  It's science, and it will make you faster.

The majority of the suits on the market get this problem dead wrong.  We did a LOT of trial and testing to get this right.  Many suits, even the most expensive, add buoyancy to the lateral or outside parts of a wetsuit, but using basic physics, it's easy to see that it is the equivalent of adding weights to your cycling shoes and pedals!  It inhibits the power phase of your stroke, makes it really hard for you to rotate properly, and makes you expend more energy.  Our patent-pending suit design enhances the power phase of your stroke and encourages quick, easy rotation along your centerline.  And if you over-rotate when you swim, you will be able to feel that more easily in our suit.  All of that translates to faster swimming with less effort.

Tech Specs

Yamamoto Neoprene

For the SIM Pro II, we use the exact same materials as its big brother, the Maverick Pro Wetsuit. This provides the exact feel you'll have on race day. "Training Like You Race" begins with developing precise muscular and neurological adaptations — the SIM Pro II lets you do that.

The SIM Pro II is 100% premium Yamamoto neoprene from Japan.  We use Yamamoto #39 SCS coated neoprene in varying thicknesses and use Yamamoto's Aerodome neoprene on the centerline (front and back).  #39 is a long-time favorite in premium triathlon suits and offers an excellent balance of performance and cost.  For the waistband, we use an advanced textile from Yamamoto to provide a better seal from water entry and folded neoprene can provide.  SCS is Yamamoto's proprietary hydrophobic surface coating.  For the centerline panel, Yamamoto Aerodome is a sandwiched neoprene that contains a perforated layer between two solid layers.  This composition traps air inside little chambers and improves buoyancy while reducing weight.  

Frequently Asked Questions (FAQ)

Q: What is the difference between the SIM Pro II and the original SIM Pro?

There are two main differences:

  1. We've added a new textile waistband construction that allows for a better seal so that less water enters the suit when diving into the pool, pushing off a wall, or swimming.
  2. We've also fine tuned the fit to provide more comfort and to cover more body types.

Q: Can I wear the SIM in a race?

  • The SIM is considered by USAT rules to be the same as a wetsuit. Therefore, you may wear the SIM in a race where wetsuits are permitted, but you may not wear it in a non-wetsuit race.

Q: Can I wear the SIM in the pool?

  • Yes, absolutely. The SIM was designed for pool swimming. Just rinse it with fresh water after use and hang dry inside out.  

SIM Size Chart


  • Our SIM buoyancy shorts mimic the materials and fit from its big brother, our Maverick wetsuit line. This provides the exact feel you'll have on race day. "Training Like You Race" begins with developing precise muscular and neurological adaptations.
  • Use the body measurement chart below to find the size that fits you best. The waist circumference is measured ~2cm above the navel (narrowest part), while the hip circumference is measured at the widest point around the hips.
WAIST: <29" - 30"
HIPS: <35" - 36"
WAIST: 31" - 32"
HIPS: 37" - 38"
WAIST: 33" - 34"
HIPS: 39" - 40"
WAIST: 35" - 36"
HIPS: 41" - 42"
WAIST: 37" - 38"
HIPS: 43" - 44"
WAIST: 39"+
HIPS: 45"+
WAIST: <74cm - 78cm
HIPS: <89cm - 93cm
WAIST: 79cm - 83cm
HIPS: 94cm - 98cm
WAIST: 84cm - 88cm
HIPS: 99cm - 103cm
WAIST: 89cm - 93cm
HIPS: 104cm - 108cm
WAIST: 94cm - 98cm
HIPS: 109cm - 113cm
WAIST: 99cm+
HIPS: 114xm+
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