The Manfrotto 357 Pro Quick Release Adapter adds professional
quick release convenience to tripod heads that don't include one
already. It gives you the freedom to remove the camera from the head and
put it on any other support. The plate features over 3" of sliding
travel, and comes supplied with two 1/4"-20 and two 3/8" camera screws.
In addition, it also includes a spring-loaded video pin. It's compatible
with the 526 Manfrotto Pro video head.