These are a CNC molded wheel side mount adapter for the Indian Chieftain  to allow a deeper speaker to be mounted with enough room for proper ventilation. Max mounting depth will vary by bag manufacture.

Fitment will also vary by bag manufacture.  Using a Quality bag or stock bag will achieve the best results. The inside diameter may have to be opened slightly as there are different speaker manufactures on the market. stainless steel outer ring hardware. 

It is recommended but not necessary to use a 2 part epoxy to bond the adapter to the saddle bag. A good example would be 3M 08115. You should also have some knowledge of body work as you will be cutting the saddle bag.

These are made per Order, depending on demand rings can take a couple days to make a set.