What does IP68 mean?

IP68 is an inter­na­tio­nal­ly stan­dard clas­si­fi­ca­ti­on sys­tem, which descri­bes the com­ple­te fea­tures of a par­ti­cu­lar device in terms of it being dust-pro­of and water­pro­of.  The term NEMA 6 is reco­gni­zed in the USA.