These couplers are designed to affix your Atibal IGNITE Thermal Imaging Optic to the objective lens of your scope. 

The multiple sized couplers utilize rubberized shims and an adjustable quick detach lever to ensure each diameter coupler size will be compatible with a range of objective lens diameters.

The fixed size couplers are specific to the outside diameter of the objective lens of your scope.  The couplers are equipped with a pre-affixed rubber lining designed to both protect your optic while ensuring a secure fit.  You will need to determine the exact outside diameter of the objective lens of your optic.

PLEASE NOTE: FIXED 39mm COUPLERS & FIXED 52mm COUPLERS REQUIRE A REDUCING RING IN ORDER TO WORK WITH THE IGNITE THERMAL.  TO ORDER BOTH THE COUPLER AND THE REDUCING RING SELECT THE APPROPRIATE PRODUCT OPTION.

To determine which coupler diameter is right for you use a set of calipers to measure the outside diameter of the objective lens, be sure to measure in millimeters.  Once you have determined the objective lens diameter that is right for you simply choose which coupler your desired diameter fits into.    [/summary]