A-Tec A-lock M18x1 is a suppressor mounting adapter, allowing quick installation and translation of the exhaust device to another weapon.
A-Tec A-lock - adapters and accessories for mounting silencers
The adapter comes in several length versions and is screwed directly onto the barrel thread. Thanks to the side bolts, attaching the exhaust device to the barrel with the A-Lock adapter takes a few seconds and requires no tools. All you have to do is put the suppressor on and rotate it 60° using similar force/torque as with regular threads. If you have several weapon units equipped with A-Lock adapters, you can quickly and conveniently reposition and install the suppressor/exhaust brake on another unit even while hunting.
Note that the A-LOCK adapter must be properly installed on the barrel of the weapon, so it is recommended that the installation be done by a qualified gunsmith.
