... LR1131 button cell;Batter replaceable;Product Specs:Material: 6061 Alloy, Silicone CNC Machine workedColor: Anodized black,red,blue,whiteLED color: redNet ... -23mm)Instruction for installation:Tighten up the screw,flatten the silicone ball, to adjust the size of the diameter,then insert directly ... the vehicals,for night riding safety.Function:Press the white silicone lens,the light will turn on .