Bolt - 1/4in x 9/16in x 26tpi, zinc plated. CEI/ BSCY cycle thread, slightly domed head, original head height. Norton AJS matchless Triumph style pre 1960s. Matchless and AJS knee pad plate bolt. Use for mudguards etc where 1/2" bolt is too short and difficult to place. Original part number STD-170; 000170 knee pad plate screw