The Extension Mount attaches under the wing nut of Ikelite handles or trays, moving the #4200 Digital Meter mount farther from the handle while providing aiming adjustment in any direction. The #4074.2 attaches to the top or bottom of SLR-MD Case handles and to the bottom of the new Release Handles. Ikelite believes it could also be bolted to some "non standard" arms from other manufacturers (check with Ikelite).