This is an aluminum standoff spacer set by Hot Racing FEATURES: Construction: aluminum Color: silver anodized YOU WILL RECEIVE: Four spacers for each of four different heights. (16 spacers total) four 2mm four 4mm four 6mm four 8mm REQUIREMENTS: Assembly on any project vehicle. SPECIFICATIONS: Outside diameter of standoff: 5.65 mm (.221 ) Inside diameter of Standoff: 3.12 mm (.123 ).