Arena Powerfin PRO II Fins (inches)
| Size | Men's US Size | Women's US Size | Fin Width | Fin Height |
| XS | 4.5-5.5 | 6-7 | 6.3 | 11.8 |
| S | 6-7 | 7.5-8.5 | 6.7 | 12.2 |
| M | 7.5-9 | 9-.105 | 7.1 | 12.8 |
| ML | 9.5-10.5 | 11-12 | 7.3 | 13.4 |
| L | 11-12 | 12.5-13.5 | 8.1 | 14 |
| XL | 12.5-13.5 | 14-15 | 8.5 | 15 |
Arena Unisex Powerfin Fins (inches)
| Men's US Size | Fin Width | Fin Length |
| 2-3 | 5.5 | 11.4 |
| 4 | 5.7 | 11.8 |
| 5-6 | 5.9 | 12.2 |
| 7-8 | 6.1 | 12.6 |
| 8-9 | 6.3 | 13 |
| 10-11 | 6.5 | 13.4 |
| 12 | 6.7 | 13.8 |
