Had a hand in creating these, and made the mistake of not asking for a royalty on them. Man, they’ve sold a lot of these. My bud Justin Stailey, responding to my complaints (what else?) came over to my studio years ago, and cobbled this together from existing Manfrotto off the shelf parts. Hence, the Justin clamp was born.
Now just updated to a clamp with metal “jaws.” Info in the blog below!
More about Manfrotto Spring Clamp w/ Flash Shoe (a.k.a The Justin Clamp)