The 4000 series is a unique range of respirators with integral filters designed for effective and comfortable protection against many gases, vapours and combination particulate hazards found throughout industry. · · · Maintenance free design for maximum safety and simplicity · · No maintenance records are required if disposed of within one month · · Replace after 28 days or when damaged, breathing resistance increases or breakthrough occurs, whichever occurs first · · 2 large bonded carbon filters for low breathing resistance · · Low profile design for better peripheral vision · · Low resistance parabolic valve to reduce heat build-up · · Soft/Non-allergenic face piece material · · Lightweight and well balanced design · · Cradle head harness · · Easy to fasten neck strap