Here is a neat idea and im surprised no one thought of it until now. These convert your flat top batteries into nipple tops. Much safer than magnets which can slide around and cause a short. So for those PV's that require nipple tops or you need a bit of length in your battery - check these out.
THE HARD COPY:
Flat Top Battery Adapter
This is an adapter that turns any flat-top battery into a button-top battery. Simply place the adapter on top of your flat-top battery to simulate a button-top. Some devices won't accept flat-top batteries, so this is a great item to keep around in case you stumble upon one such device. Adds minimal length and resistance to the battery.
WHERE: >>> HERE <<<
$2.49