Puma Sierra Nevada Safety Boot With Composite Toe Cap BIOSECURE What does the FO rating

What does the FO rating mean on these safety shoes

Construction: 100% vegan materials

Constructed from high grade scuba neoprene and layers of hand laid rubber for maximum performance and durability these boots have kept workers dry and comfortable for more than two decades

For workers who require additional width or have broader feet

Puma Sierra Nevada Safety Boot With Composite Toe Cap BIOSECURE What does the FO ratingQuality full leather upper, BreathActive functional lining keeps feet fresher for longer whilst the Evercomfort footbed makes for a very comfortable fit. Eye catching design makes these a stylish choice of safety footwear. CompositeCap and flexible FAP midsole, CORDURA and SYMPATEX Greased full leather upper BreathActive functional lining Evercomfort footbed Rubber sole scruff caps with EVER. FLEX decoupling point and 300oc heat resistance