Check the listing for details. 5 PACK- DEAD END PLUG Tee, New Cutting Edge Tech 3/16" Maple Sap Tees. Condition: New. Listed at 12.99 USD. 5 PACK - Brand New - Fit 3/16" ID Tubing!! These are the Blue DEAD END TEES. These are for the last tree on your line. One barb is plugged so that the tubing section that wraps around your tree is not connected to the system, it is isolated. 5-PACK. You get 5 of the fittings pictured. These new 3/16" end of line PLUG-TEES can be used with any 3/16" ID maple tubing. One Plugged Barb goes into the tubing on the end of your maple line and when you wrap the maple line around the tree and use either an End Hook or an End Ring to secure the end of the tubing to your line.. These are used at the LAST TREE on your sap line. This prevents leaks where the tubing wraps the whole way around the tree from interrupting your sap flow. This fitting essentially blacks off the sap from entering the last piece of tubing that wraps around the tree. This section is a place where sap often pools and spoils and it's one of the squirrels favorite places to chew! So blocking it off is very beneficial!