Permanent & Removable Rail Mount Clamps fit 3/4" to 1-1/4" tubing.  Shims, thumb screws and all mounting hardware are included with purchase. This product is great for mounting solar panels and a wide variety of other items to your existing rails / bimini, weight dependant.  

Specifications:
Injection Molded Nylon / Stainless
A: 3/4" - 1-1/4"
B: 3-7/8"
C: 1-7/16" 
D: 2-1/2" 
E: 7/8"