These are used at the ends of the metal hoops which hold up the fabric on a bimini. We have inserts and caps for both 3/4" and 7/8" tubing. Usually Aluminum is used, but we have found that the inserts for 3/4" tubing are almost a perfect fit in 1/2 steel electrical conduit (emt) which you can get from your local lumberyard. In fact, in the photo above, the insert (on the left) is in a piece of such tubing. If you will not be using your boat in salt water and desire a cheap and available material for your bimini, consider steel. You can buy a bender where the conduit is sold and the stuff can be painted or left galvanized.
No matter whether you use tubing or pipe or what, you need to know the actual size of the stuff you are using and make sure that it will mate with these parts. Below are the dimensions of the parts. You will want to have a 5 or 10 thousandths of play for a good fit.
PLEASE NOTE: Depending on the material used for tubing, our bimini parts may not fit the way you expect. Please see our drawings (below) with ID (inside diameters) and OD (outside diameters) and compare those with the dimensions on your specific tubing to determine the correct size of bimini parts you need. Thank you!