Safariland came up with the new locking system called GLS(Grip Locking System). This system unlocks the gun when the shooter grabs the pistol and the middle dinger will touch the holster.
Currently, they are availabe for Glock 17, 19, 22, 23, 26, 27, S&W M&P(full size, compact and Shield), and SA XD, XD-s and XD(M)
Price: $46.50
Here's a review from The Tactical Wire
From: Safariland
