If you're shopping Rehband knee sleeves in the UK, you'll quickly hit the same fork in the road every CrossFitter does: 5mm or 7mm? Both are excellent. Both have a job. They are not the same sleeve in different thicknesses — they're built for different training. Here's the honest, no-marketing-hype guide.

The short answer

• Buy 5mm if you do mixed CrossFit — metcons, gymnastics, running, plus your strength work. Most CrossFitters should start here.
• Buy 7mm if your training is squat- and strength-biased, you're a taller athlete, you're a competitive weightlifter or powerlifter, or you want maximum support and warmth on heavy days.
• Own both if you're serious about training: 5mm for daily WODs, 7mm for max-effort squat sessions and strength blocks.

What the numbers actually mean

5mm and 7mm refer to the thickness of the SBR/neoprene the sleeve is made from. That extra 2mm doesn't sound like much, but in practice it changes three things:

• Compression and rebound. Denser neoprene rebounds harder out of the bottom of a squat. The 7mm gives you a tangibly stronger "pop" at the bottom; the 5mm is gentler.
• Warmth. Thicker = warmer. The 7mm warms the joint faster on cold gym mornings. The 5mm runs cooler on long sessions.
• Mobility and breathability. The 5mm is noticeably more comfortable for high-rep workouts, double-unders, running and gymnastics. The 7mm starts to feel hot and restrictive when you're doing a 20-minute metcon.

Rehband RX 5mm — the everyday CrossFit knee sleeve

The Rehband RX Knee Sleeve 5mm is the default. It's the most-used knee sleeve in CrossFit globally for a reason: it sits in the sweet spot between support, warmth and mobility. You can wear it through a full session — strength, then a metcon, then accessory work — without it becoming a problem.

If you're a CrossFitter who does a typical mixed-modal training day, the 5mm is the right choice. It's also the right choice if you're newer to lifting and not yet putting heavy enough weights overhead or on your back to need maximum support.

Rehband RX Knee Sleeve Power Max 7mm — the heavy-lifting choice

The Rehband RX Knee Sleeve Power Max 7mm is built for one thing: heavy lifting. Powerlifters wear them. Olympic lifters wear them. Games-level CrossFitters wear them on strength days. The 7mm gives noticeably more rebound out of the hole on back squats and front squats — useful when you're working at 85%+ of your max for triples and above.

The Power Max also runs slightly longer, which makes it the obvious choice for taller athletes (roughly 6'+) who find the standard 5mm sleeves sit too low on the leg or feel under-supportive. If your femurs are long, this is the sleeve for you.

What about the 3mm?

You'll see Rehband 3mm sleeves on some other UK retailers' sites. They're aimed mostly at runners and rehabilitation use — think shin splints, mild compression for endurance, or warmth for cycling. For CrossFit, weightlifting and powerlifting, they're too thin. Stick with 5mm or 7mm. WORKIT stocks 5mm and 7mm only because that's what the lifters we serve actually use.

Sizing — the part most people get wrong

Rehband sleeves are sized to a specific measurement: the circumference of your leg 15cm above the centre of your kneecap. Get a soft measuring tape, mark the spot, measure, and match to the size chart on the product page. Two important rules:

• Do not size up. A loose sleeve does nothing. Tight is the point.
• If you're between sizes, size down. They'll feel firm at first — they're meant to. They'll break in within a week.

The 7mm Power Max uses a slightly different chart from the 5mm. Always check the chart on the specific product page, not your memory.

How long do they last?

With daily training, expect 12–24 months before noticeable stretching. To extend their life: hand-wash cold, never machine-dry, never iron. Most athletes get 18 months out of a pair before they want a fresh one.

Buying Rehband in the UK

WORKIT is your official UK Rehband stockist. We ship from UK stock with GBP pricing, no customs surprises, and free UK delivery on orders over £100. You can browse the full range on our Rehband UK collection page, including the X-RX Lifting Belt, X-RX Wrist Wrap, RX Elbow Sleeve, and RX Shin/Calf Sleeve.

If you're still not sure whether to go 5mm or 7mm, the safe answer is: 5mm first, 7mm later when you start chasing real numbers under the bar. We use these ourselves — they're reliable, they last, and they do the job they're built for without any marketing hype.

FAQ

Are Rehband knee sleeves CrossFit Games legal?
Yes — neoprene knee sleeves like the Rehband RX (5mm and 7mm) are permitted under CrossFit Games rules. The 2025 rule change about "rubber-based grips" doesn't affect knee sleeves.

Can I wear 7mm sleeves all day?
You can, but it's not the most comfortable choice. They're warmer and tighter — great for squat sessions, less great for a 30-minute metcon. Most people who own both reach for 5mm 80% of the time.

Do Rehband sleeves come as a pair?
The RX 5mm and RX Power Max 7mm are sold as single sleeves on Rehband's standard pricing. Order quantity 2 if you want a pair, which most people do. The X-RX Wrist Wrap, by contrast, ships as a pair already.

Does WORKIT do free returns?
Free UK delivery applies on orders over £100. Return policy details are on the product pages — standard 14-day rules apply for unworn, unused items.

Questions about which sleeve is right for you? Drop us a message on Instagram @workitcrossfit or WhatsApp +44 7508 305348.