the ones that AVPfan pointed out are perfect. You can find them on ebay if you search "rare earth magnets" hopefully that is what is inside the head as well. If the magnets in the head are week, then it really wont matter what you pair them with. If you need to re-install ..slice the foam with a razor ...work your finger into the hole until you hit the latex of the mask...separate some of the latex and the foam and slip a magnet with some flexible glue ( gorrilla, shoe goo, barge) under the skin of the mask. Find the corresponding magnets and mark where the would be placed on the bio. glue them down ..but use something more to re-enforce the bond (rim plumbers epoxy around the magnets for example) Also ..before attaching those magnets to the bio ..make sure the polarity is correct ..you'd hate to install them on the bio and watch as the mask and bio repel each other