High quality ring nuts for Riddler wheels. The truck I mounted them on has front wheel spacers and these ET nuts allow the nut to go into the hole so you don't lose threads through the thickness of the spacer, in this case a 1/4-in -Spacer.
Pros
REQUIRED: 13/16 in. (21mm) and 22mm hex tool/wrench #D5110K for installation and removal (sold separately). Wheels must be centered on cleats with a 16mm eyelet hole.