Type 99M wire has a dual-wall construction of radiation cross-linked modified polyester. It is designed to meet the stringent low fire hazard performance specified by many authorities, in particular for naval, mass transit and industrial panel wiring.

Type 99M wire is highly flame retarded and has low smoke and corrosive gas generation whilst still retaining small size, lightweight, flexibility and resistance to chemicals and fluids.Type 99M wire is approved to Def-Stan 61-12 Part 18 Issue 4 Type 1.