This is a list of Glock models as I cannot ever seem to remember all of them and wanted a quick reference.

G17, 9mm Luger, 17 round magazine, 4.5” barrel, 1.18” width

G18 is the same as the G17 but it is a select fire weapon (it may be fired fully automatic) and sales are to law enforcement only. It is usually equipped with a 33 round magazine. That magazine will fit any 9mm Glock. Another note on magazines for Glocks. Of pistols in the same caliber, any higher capacity magazine will operate in a pistol that comes standard with a lower capacity magazine. So, a G17 17 round magazine will work in a G26, which normally uses a 10 round magazine.

G19, 9mm Luger, 15 round magazine, 4” barrel, 1.18” width

G20, 10mm Auto, 15 round magazine, 4.6” barrel, 1.27” width

G21, 45 ACP, 13 round magazine, 4.6” barrel, , 1.27” width

G22, 40 S&W, 15 round magazine, 4.5” barrel, 1.18” width

G23, 40 S&W, 13 round magazine, 4” barrel, 1.18” width

G25, 380 ACP, 15 round magazine, 4” barrel, 1.18” width. This model is basically a G19 in 380 ACP. It is not sold in the United States.

G26, 9mm Luger, 10 round magazine, 3.5” barrel, 1.18” width

G27, 40 S&W, 9 round magazine, 3.5” barrel, 1.18” width

G28, 380 ACP, 10 round magazine, 3.5” barrel, 1.18” width. This model is basically a G26 in 380 ACP. It is not sold in the United States.

G29, 10mm Auto, 10 round magazine, 3.8” barrel, 1.27” width

G30, 45 ACP, 10 round magazine, 3.8” barrel, 1.27” width

G31, 357 Sig, 15 round magazine, 4.5” barrel, 1.18” width

G32, 357 Sig, 13 round magazine, 4” barrel, 1.18” width

G33, 357 Sig, 9 round magazine, 3.5” barrel, 1.18” width

G34, 9mm Luger, 17 round magazine, 5.3” barrel, 1.18” width

G35, 40 S&W, 15 round magazine, 5.3” barrel, 1.18” width

G36, 45 ACP, 6 round magazine, 3.8” barrel, 1.13” width

G37, 45 GAP, 10 round magazine, 4.5” barrel, 1.18” width

G38, 45 GAP, 8 round magazine, 4” barrel, 1.18” width

G39, 45 GAP, 6 round magazine, 3.5” barrel, 1.18” width

Holsters are interchangeable between any Glocks having the same width and barrel length. If the model number is followed by “SF” that refers to Short Frame, these models have a slightly shorter front to back grip length at the bottom of the grip.