Serrated (shakeproof) washers are meant to prevent the risk of attachments becoming loose when used in conjunction with a locknut.
These are available in both galvanised mild steel and stainless steel.
Capri ECP - Plastic industrial cable glands
Capri UNICAP - Plastic industrial cable glands
Capri EUROCAP - Plastic industrial cable glands
Capri NEWCAP - Metallic industrial cable glands
Capri ISOCAP & NORMADIX - Metallic industrial cable glands
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