Yep, wot he said.
The Bipod has a rare earth magnet on the end of the boss and this attracts itself to the countersunk stainless screw that retains the Adapter to the stock, providing a fairly strong connection.
The alternative to this is to buy the "gunsmith insert" which you bond into the stock. It mounts flush and has a small disc inside to which the magnet attracts. Either way the result is the same... the bipod doesn't fall out.
Bookmarks