Senco EA0141 #2 Square Bits - Duraspin Technology Integrated Auto-Feed Screw System Compatible with Duraspin models: DS300-AC and DS274-18V For use with Tyrex models: D600-AC and D550-18V Genuine Senco Replacement Part Made with Steel to Hold up in Demanding Applications (2) #2 Square Duraspin/Tyrex Bits Per Package