... to 370 degree; 3.usded for heat and frame protective garments; 100% Spun Kevlar Fire-retardant Sewing Thread It is made of ... and flame up to 370°C.It is is used for sewing heat and flame protective garments, public authority garments, tents, etc ... /2, 30/3, 40/2, 40/3, etc. fire retardant sewing thread