This is the Muffler Screw Set for the #744B and E4020 OSMG2840 OS Max mufflers. They are used to mount the muffler to the engine. FEATURES: Black Steel Construction INCLUDES: Two 4mm x 40mm Cap-Head Mounting bolts (Shouldered) SPECS: Cap-Head screws feature a .7mm coarse thread. COMMENTS: A 3.0mm allen wrench is required for tightening the Cap-Head screws. NNA 1/6/02 updated tjt 042605