The 6.1mm Glock rear steel sight that fits all Glock pistols. This will have a point of impact 3" lower than the 6.5mm rear sight at 15 yards. Standard sight for the Glock 17L pistol.
Glock Polymer Rear sight adjustable (OEM) fits all Glock models except G42/43. New style does not extend over back of slide. Part number 2 on the Glock Schematic.