This is an adapter made by Universal Astronomics to allow photo heads or small EQ heads with 3/8" holes to be used on a surveyor's tripod (which normally has a 5'8" stud). I used it to mount my MiniEQ (now sold) to a surveyor's tripod. It's just a round 3" diameter aluminum plate with a 3/8" bolt, but it works. Remove the stock mounting stud from the surveyor's tripod, place the plate underneath the large hole in the tripod, and tighten it to your head with the bolt. If you have a head with a 1/4" mounting hole, you can get a 3/8" to 1/4" adapter by Bogen at any photo shop. New from Universal Astronomics, it's $20 + shipping. From me, it's $17 shipped. I suppose I can take a photo on request, but there's really not much to see... I take Paypal, money order, or personal check if you have more than 10 positive feedbacks & no negatives.
SOLD - Thanks, Geoff!