Swarovski TMA56 thermal monocular adapter allows to convert from a hand-held device to a clip-on device. 

The TMA56 thermal monocular adapter is compatible with SWAROVSKI OPTIK: dS, Z8i, Z6i, Z5(i) and Z3 riflescopes.

The thermal monocular adapter is made from aluminum.

The number refers to the objective lens diameter of the rifle scope.