There are two sizes of gaskets required for the 3+1/4inch Pre-WW1 Davison sight glass. A 31mm OD gasket to fit in the top cap and a 29mm OD gasket to fit on the base of the glass.
One Top gasket and one Base gasket should be installed.
In the kit there are 2x 2mm and 3mm thick gaskets (4 gaskets in total)
Part Nr 62-462 Enots dome oil sight glass base Gasket
This gasket sits under the base of an Enots dome oil sight glass.
There is a 2mm thick neoprene impregnated cork gasket and a 3mm thick gasket in the kit to cope with various thread lengths on the pumps over the decades . In unusual cases where a 4mm thick gasket is required consider purchasing two kits and place a 2mm gasket on top of another 2 mm gasket to achieve 4mm . Please read the secondary information below regarding estimating the thickness required.
Douglas Flat Tank- Oil sight glass and gasket kit.
The kit comprises a 39mm diameter ,2mm thick, hardened sight glass plus a top and a base gasket. In addition, there is also a fine metal shim in the kit which is placed below the base gasket
Part Nr 66-462 Triumph oil sight glass and gasket kit
The engine mounted sight glass and gaskets for the late 1920s early 1930s Triumph. Models TT, ST, W, WS, N & NSD. This sight glass is best suited to the type of sight glass holder with the Screw-in type of retaining ring for the glass and gaskets and not the Push-fit type of retaining ring