This is a Bianchi Holster known as the 5, model 15718.
The Black Widow belt slide holster is an ultra hi-ride carry with a thumb snap closure. Dual belt slots provide stability and the open muzzle design offers fits for same pistol models with differing barrel lengths. Compact profile and widely spaced belt slots allow the pistol to ride close to the body for both comfort and concealability.
Features:
#5 OWB
Belt slide holster
Right hand
Fits Glock 17/19/22/23/26/27/34/35