D9/M8 Collar Screw.If the thread of the engine casing is severely damaged or torn, it is no longer possible to tighten the standard screw to the established tightening torque and locking of the screw is no longer guaranteed. In this case it can be remedied using screw 0000 664 2414.Models: MS 271 C-BE MS 291 C-BEQ MS 291 C-BE