This product will upgrade a pre 2005 BSD sail kit where the cross tube and the Aka tube are joined by a single layer of tubing. The Doubler kit adds a second inner tube to help distribute the load across the take apart joint area. To install this kit you will need to extract the current tubes that reside in the cross tube and Aka. They are held in with 2 #10x 3/4 SS screws and a roll pin. Remove all 4 of them and place the male side into cross tube facing out and secure with SS roll pins provided. Once sleeved into Aka tube drill through Aka using old screw holes to set # 10 screws. You will also need to drill a new the 1/4" hole for the fast pin.
More pics coming soon or call if you need clarification.