[3 screws]Toppers Stay firmly with 3 set screws and Rubber Insert. Rubber Insert also protects the pedal switch.[For 3/8inch 10mm Switches]Outer Diam 23mm Inner diam 10mm for use on common 3/8inch 10mm Effects Pedal Switches. Not fit on other size switch.[Increase Accuracy Comfort]Easier to see and hit with bigger . No sting to your feet. And your pedalboard looks better and more like an upgrade.[aluminum]Duraluminum Durable never and everlasting color by anodic oxidation finish.[Installation]Press to the switch fully as you tighten the set screws.colour:silverMaterial:Aluminum alloysize:Product Size:External size 24 x 12mmInner diameter 10.4 x 20mmPackage Contents:10 x guitar effects capOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.