The Lenzi L-protection barrier protects the bottom of the foot from puncture wounds caused by nails, iron shards, glass and scrap metal. Exceeds ASTM F2413-05 requirement for a puncture resistant midsole by 70 lbs. The P4 barrier is non-metallic, which makes it itdeal for colder climates. Added heel cushioning, for all-day comfort. Micro fiber top sheet to reduce slip and hot spots underfoot.