This 1/4" thick steel spacer can be used to lift the height of your Superduty high steer arm on a Reid Racing Superduty Knuckle or provide a cap for the top of the knuckle. Works on either passenger or driver side. Hardware not included but the knuckles uses a 1/2 20 tpi thread which can be sourced at any hardware store. ARP studs not necessary when using as a cap.