Wheelchair Bridge Clamps:

1" (WC-R1B) and 7/8" (WC-R7/8B)

The bridge clamps are smaller than the full sized round clamps, and must be used in a pair.
Bridge clamps are used to clamp to multiple tubes, eliminating the possibility of clamp-slip. We recommend this method for heavier devices. An adapter plate (either the WC-AP2 or WC-AP4) is used to span the two bridge clamps - and the Wheelchair Brackets or extensions bolt directly to it.

To implement bridge clamps, you will need at least two bridge clamps and a plate to span them (WC-AP2). Each individual bridge clamp should be appropriately sized to the tube that it clamps to.
Eg: (Tubing that is 7/8" in diameter should use the 7/8" bridge clamp.)
The strongest mounts will be if you can get both clamps perpendicular (90°) to each other.

Collar Clamps

Collar Clamps can also be used to "bridge" across a curve or to span a 90° angle on the chair frame.  They can be used in conjuction with a bridge clamp (ie. one collar clamp, and one bridge clamp)