Usage Tips:[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 very common 3/8inch 10mm Effects Pedal Switches. Not fit on other size switch. [Increase Accuracy Comfort]Easier to see and hit with bigger target. No sting to your feet. And your pedalboard looks better and more like an upgrade. [aluminum]Duraluminum Durable never crush and everlasting color by anodic oxidation finish. [Installation]Press to engage the switch fully as you tighten the set screws. colour:silver Material:Aluminum alloy size: Product Size: External size 24 x 12mm Inner diameter 10.4 x 20mm Package Contents: 10 x guitar effects cap Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.