Flange Fix Sheath (3 Pieces) For 105-135 Gear Box of 4 Stroke (178F, 186F, 188F & 177F) Power Tiller is a specialized set of gear box sleeves used in the shift gear assembly of micro tillers with 4-stroke engines (compatible with models 178F, 186F, 188F, and 177F). These flanged sheaths provide structural support, ensuring stable alignment and smooth shifting in the gear box.