Estimated reading time: 12 minutes
Table of Contents
- What Is the Castiron Grip PR23?
- Who Is the PR23 For?
- Aggressive Downturn — Why It Matters
- Dual Velcro Closure System
- High-Friction Rubber Sole
- Sizing Guide — USA & Canada
- PR23 vs the Castiron Grip Line
- Formerly Rock Planet — Now Castiron Standard
- Verdict
What Is the Castiron Grip PR23?
The Castiron Grip PR23 is a performance velcro climbing shoe built for climbers who've stopped guessing and started committing. Aggressive downturn, dual velcro closure, and a precision rubber toe patch that reads the hold before you do. This is the shoe for advanced climbers who need their gear to match their standard — whether that's projecting V7 at your local gym or sending technical face routes at Red Rock or Squamish.
At $109 USD, the PR23 sits in the performance tier without the premium price tag of European competition shoes. Available in Yellow and Blue colorways, EU 35–44.
Who Is the PR23 For?
The PR23 is built for climbers who have moved past beginner flat shoes and need a tool that performs on harder terrain. Specifically:
- Indoor bouldering — overhangs, compression problems, pocket pulling
- Outdoor sport climbing — technical face, vertical edging, limestone pockets
- Competition prep — fast transitions between problems, secure fit under pressure
- Advanced climbers — V5 and above, 5.11+ on routes
If you're climbing V4–V5 consistently and your flat shoe is holding you back on steep terrain, the PR23 is your next move.
Aggressive Downturn — Why It Matters
The downturn of a climbing shoe determines how your foot loads the hold. A flat shoe distributes pressure evenly — comfortable for long routes, ineffective on steep terrain. An aggressive downturn like the PR23 concentrates force through the big toe, giving you precision on small holds and power on overhangs.
The PR23's aggressive downturn profile puts your toe in the optimal position for:
- Overhangs — toe hooks, heel hooks, compression moves
- Pockets — two-finger and mono pockets on limestone and sandstone
- Technical face — small edges on vertical granite and quartzite
Note: aggressive downturn shoes are not designed for all-day comfort on multi-pitch routes. The PR23 is a performance tool for hard bouldering and sport climbing sessions, not a trad shoe.
Dual Velcro Closure System
The dual velcro closure on the PR23 is one of its strongest features for gym climbers and boulderers. Between problems, you can loosen both straps in seconds, let your foot breathe, then lock back in before your next attempt.
Compared to lace-up shoes like the Castiron Grip SWIFT, the PR23's velcro system trades micro-adjustability for speed. For boulderers doing multiple attempts on a single problem, this is the right trade-off.
High-Friction Rubber Sole
The PR23 runs a high-friction rubber compound across the full sole and toe patch — optimised for indoor gym walls and outdoor limestone, the two most common surfaces for advanced climbers in North America. The precision toe patch extends rubber coverage to the very tip, giving you confidence on small footholds and smears.
Sizing Guide — USA & Canada
The PR23 runs small due to its aggressive downturn. Size up 0.5–1 EU from your street shoe size. Women should size up 1.5 from men's US sizing.
| EU | US Women | US Men | UK |
|---|---|---|---|
| 35 | 5W | 3M | 2.5 |
| 36 | 6W | 4M | 3.5 |
| 37 | 6.5W | 4.5M | 4 |
| 38 | 7.5W | 5.5M | 5 |
| 39 | 8.5W | 6.5M | 6 |
| 40 | 9W | 7M | 6.5 |
| 41 | 10W | 8M | 7.5 |
| 42 | 11W | 9M | 8 |
| 43 | 12W | 10M | 9 |
| 44 | 13W | 11M | 9.5 |
Free shipping on US orders over $150. Ships from our US warehouse. Standard delivery 5–8 business days. Expedited 2–4 business days.
PR23 vs the Full Castiron Grip Line
Not sure which model is right for you? Here's how the full lineup stacks up — click any model to go straight to the product page.
| Model | Closure | Downturn | Best For | Level |
|---|---|---|---|---|
| PR23 (this shoe) | Dual Velcro | Aggressive | Bouldering, overhangs | Advanced |
| N23 | Dual Velcro | Moderate–Aggressive | Precision edging | Intermediate |
| SWIFT | Lace-Up | Moderate | All-round, sport climbing | Beginner–Intermediate |
| Little ALIEN | Slip-On | Flat | Kids beginner | Youth Beginner |
| ONE | Velcro | Flat | Youth development | Youth |
| HUG | Velcro | Flat | Kids first shoe | Kids Beginner |
→ Browse the full Castiron Grip collection
Formerly Rock Planet — Now Castiron Standard
The PR23 was formerly available under the Rock Planet brand — same construction, same last, same proven rubber compound. Rock Planet built a strong reputation in the climbing community for accessible performance footwear, and that DNA carries directly into the Castiron Grip line. If you climbed in Rock Planet shoes, you already know what the PR23 delivers.
The Castiron Grip line represents the next chapter: unified brand standards, expanded sizing, and a next-generation model lineup arriving in 2027. The PR23 is the current generation — and it's the same shoe that earned Rock Planet its reputation.
Verdict
The Castiron Grip PR23 is a no-compromise performance bouldering shoe at an honest price. Aggressive downturn, dual velcro, high-friction rubber — everything an advanced climber needs to step up their game without overpaying for a brand name.
$109 USD. EU 35–44. Yellow and Blue colorways. Free shipping on US orders over $150.
Castiron Grip PR23 — Performance Velcro Climbing Shoe
Aggressive downturn · Dual velcro · High-friction rubber · EU 35–44
→ Shop the PR23 — $109 USDExternal Resources
- USA Climbing — National Federation
- Climbing Canada — National Federation
- IFSC — International Federation of Sport Climbing
- Mountain Project — Route Database USA & Canada
- 99Boulders — Climbing Shoe Buyer's Guide
Written by T-K