Thomas Service Kit. Kit includes 624285 piston cups, cylinder sleeves, cylinder orings, head orings, valves, valve keepers, dynamic backers, valve screws, head screws, retainer screws. Kit is compatible with standard Thomas 2660, 2680 models. (This item currently has a tariff surcharge which will be added to your order as a separate line item. Tariff surcharges are subject to change.)