The most common primer button used in chainsaws and clearing saws, used e.g. in several Efco, Jonsered, Husqarna, Stih, etc. machines. Attaches with "clips" to the hole in the case. e.g. in models: Efco MT4100SP, MT4400, MT5200, MT440 Jonsered FC2145, CS2240, CS2240S, CS2153, CS2152 Husqvarna 543XP, 543XPG, 450 II, 450e, 450, 445e, 445, 440e, 440, 435e, 435 Stihl MS210, MS230, MS250