AISEN Carburetor Primer Bulb for Troy-Bilt TB80EC YM21CS TB21EC TB22EC TB2040XP Trimmer # WT-973 Replacement manufacturer part no. 753-06170, WT-973 For MTD Bolens Troy-Bilt Yard Man Craftsman trimmer Package include: 1 x carburetor, 2 x primer bulb