Review on Powerful Neodymium Bar Magnets With Double-Sided Adhesive - Ideal For Home, Office & Scientific Uses - Pack Of 16 Magnets by Bryan Finken

These magnets are really powerful and very difficult to get apart if two come together. Only way I've found safe to separate them is sliding them apart. I bought them to help provide extra hold for register/vent covers. Typical registers when closed don't stop air flow 100% so I've purchased magnetic covers. Although they are magnetic, the covers don't hold as well on ceiling registers. The magnets will ensure a secure hold.