The NOVOFLEX QPL 450 Double-Sided Arca-Style Rail - 17.7” Long features an Arca-Swiss-style dovetail on either side, so you can attach it to a double-clamp system. For 3D applications, two cameras can be mounted to the long Q-Plate, one to each of the included 1/4"-20 screws, with horizontal positioning possible in order to adjust the interaxial distance between the cameras' optical centers. Not only do the Q-series rails feature Arca-style profiles on either side, they also have 1/4"-20 & 3/8"-16 tripod mounting holes for direct attachment to a head or tripod. Note: The NOVOFLEX Arca-type quick release plates are thinner by the slimmest of margins than Arca-Swiss quick release plates. They are not recommended for use in the Arca-Swiss Flip-Lock quick release clamp.