Nyloc nut
Product number:
321688
with 9/16" BSF thread - total height: 23/32", spanner size: 1/2" W (9/16" BS)
Product Information "Nyloc nut"
Austin Healey: BN1 and BN2 (1953-56)
with 9/16" BSF thread - total height: 23/32", spanner size: 1/2" W (9/16" BS)