-F2M 2" MPT filter thread adapter

This adapter fits into the bottom of some Pleatco filters, among others. It has a 2" MPT type thread (58-59 mm outside diameter) on one side, and on the other side a tip with four small pins that snap into slots at the bottom of the filter (diameter without pins: 59.5 mm).

It converts your Pleatco filters to "Pxx-F2M".

The thread is normally screwed to the bottom of your spa skimmer, and the adapter is used to hold the filter in place.