These are BSF Thread used on British motorcycles from years 1950 to 1968. These use a 3/16" Wrench.
Craftsman 26 millimeter x 26 millimeter x 14 in. L 12 Point Metric Combination
Stellar 31228, (4) Drawer Heavy-Duty Steel Toolbox- 16.5"H x 26"W x 14.75"D
Fel-Pro Gasket Making Material 3075; 10 x 26 in. x 0.047 in. Rubber/Cellulose
16.14"x 10.62"x 13.78" 300lb Mechanics Rolling Stool Workshop Yellow Tool Seat
16.14"x 10.62"x 13.78" 300lb Mechanics Rolling Stool Workshop Orange Tool Seat