This simple little junction made from 25 lb. or 30 lb. test Maxima can help protect the factory loops on the end of polyleaders, MOW tips or other sink-tips. Just cut a 12 inch piece of the Maxima and tie a double surgeon's loop at either end so you end up with a "junction section" that is about 3-4 inches long.
When swinging flies I like to attach a tippet of 10 lb. test Maxima ultragreen to the end of my MOW tips by making a double surgeons loop and looping it to the loop on the tip. But this relatively thin mono can cut into the factory loop on the sink-tip and shorten its life.
The solution is to make a short junction of heavier mono (25-30 lb. test) which will protect the factory loop from excessive wear. Then you just loop your lighter tippet to the end of the "junction section".