The clamp size is 2 inch, we supply 2 rubber inserts for 1″ to 1-1/4″ inch size tubing. Stainless Steel;Adjustable Fishing Rod Holder for Rails 1″ to 1-1/4″. The 5 rod holders will clamp to your T-Top, hardtop, tower, radar arch, rail or any structure made from 2 inch tube pipe (without insert), 1.5inch-1.75inch pipe (with insert). You will have a place for you fishing rods in a safe place off your floor;Stainless Steel Clamp On Adjustable Fishing Rod Holder for Rails 1″ to 1 1/4″. It Can Adjust to Any Angle. Amarine Made 2 Pack 20 Degree Stainless Steel Wall Transom Mounted Rod Holder. 2 Pcs Stainless Steel Fishing Rod Holder Outrigger Stylish Plug-in Pole Holder. 4 Pcs 15 Degree Stainless Steel Boat Fishing Rod Holder Flush Mount Rod Holder. 4 Tube Stainless Fishing Rod Holder w/ Square Clamp Adjustable Fishing Rod Rack. 2X Stainless Steel Fishing Rod Holder for Rails 1-1/4″ to 2″ Tournament Style. Amarine Made 2Pack 316 Stainless Clamp on Fishing Rod Holder for Rail 7/8″ to 1″. 6 Tube Fishing Rod Rack Stainless Steel Fishing Rod holder for Marine Boat Yacht. 4PCS Stainless Steel Boat Fishing Rod Holder Side Transom Mounted Weld Brackets. 2PCS 90 Degree Stainless Steel Tournament Style Rod Holder Wall Transom Mounted. 4PCS Stainless Steel Fishing Rod Holder Slide Mount 30 Degree Boat Rod Holder. 3 Tube Stainless Steel Trident Outrigger Stylish Rod Holder Triple Rod Holder. 2PCS Stainless Steel Clamp on Boat Fishing Rod Holder for Rails Mount 7/8″ to 1″.