FXD WB.4 Nitrolite slip on work boots are high performance double bound elastic sided work boots featuring our Nitrolite midsole technology for all day comfort. The WB.4 slip on is Australian and New Zealand standard compliant and the bonding and composite toe have been tested and certified by Benchmark Product Certification. Upper Material- Nubuck, microfiber TPU Nitrolite proprietary Phylon midsole cushioning material Slip, oil, heat resistant 62 durometer rubber sole High density 67 durometer green heel insert for increased durability Reinforced double bound elastic gusset Lightweight composite safety toe Protective TPU heel kick panel Padded achilles support insert