The HIVIZ Fully Adjustable Rear Sight for Glock pistols fits Glock Gen 1, 2, 3, and 4 all models except 42, 43 and MOS. It requires the HIVIZ front sight GLAD201. It features an all steel construction with click adjustment for windage and elevation and interchangeable LitePipes. It includes 3 sets of LitePipes in green, red and black. The LitePipe diameter is 0.070 inches.