3154 is extended 10mm longer and increases the range for left and right adjustments to mount cameras in special shapes, such as BMPCC 4K camera equipped with a cage. The distance between the two locking 1/4 screws are 18mm which is compatible with most SmallRig cages like Sony A7S III cage 2999, Canon R5/R6 cage 2982, Nikon cage 2926 for Z series cameras, etc. Moreover, the plate features an open-middle design so you can access most camera mounting screw through the plate and easily unmount the camera from the cage to move it to a tripod or other mounts. The plate also features rubber pads to protect the cage.