The JS1 Pro jockey skull is lightweight, deep-fitting and features an impact-resistant ABS outer shell with ten ventilation slots. The upgraded leather harness with reinforced nylon webbing and suede padding under the chin provides greater rider security and comfort. SEI certified to ASTM F1163-15 only on sizes 0 1/2 – 4. 10 ventilation slots Leather harness Standards: ASTM F1163-15, PAS015:2011, VG1 01-040 2014-12 Please be aware that our returns policy does not apply to Riding Helmets, Body Protectors and Made to Measure items. On items of safety equipment we guarantee that they have not been damaged or altered in any way which would affect performance. Once these items have left our premises we cannot continue this guarantee and therefore cannot accept stock back. Please contact us before returning any items.