Homelite UT10540 Chainsaw (2 Pack) Replacement Tension Knob Assembly # 307505003-2pk Genuine OEM Replacement Parts Compatible with Homelite Chainsaws Tightens and secures the chainsaws clutch cover lock knob Made out of metal with plastic This part is a merged assembly of old part# 518769001 (Cover Knob) and 678618002 (Tension Nut).