Glock REAR Sight GMS 6,5 STEEL TRITIUM GREEN (4. D

Info about Glock sights:

The idea is that Glock front sight is fixed, and you change point of impact with the Rear Sights height.

Normal set-up with Glock (17, 19) Gen 1 to 4 is Front Sight 4,1mm, and Rear Sight is 6,5mm 

Normal set-up with Glock (17, 19, 45) Gen 5 is Front Sight 4,1mm, and Rear Sight is 6,1mm 

(If you still hit high, and you feel you need a even lower Rear SIght than 6,1 (that don´t exist), then you fix it with a 4,9 Front Sight and 6,5 Rear Sight. This will be like a "5,7" Rear sight)

When i comes to high sights aimed for pistol where silencer can be attached :

Normal set-up is 9,1mm, and Rear Sight is 11,1mm (Gen5) or 11,5mm (Gen2-4).

Then, because our creator didn't make us all the same, there are other heights of front and rear sights to adjust for our different point of view...