Rubber Coated Neodymium Pot Magnet - Diameter 88mm x 35mm with Nylon P Clamp D_29mm This ferrite magnet has a

This ferrite magnet has a  magnetic flux reading of  1982 Gauss and a pull force of  9 kg

They are sometimes used to collect metallic objects and swarf in commercial premises or in other cases are used for the purpose of conditioning water

and comes with a with a 28mm boss thread

If you want a lower profile on the weekend

Rubber Coated Neodymium Pot Magnet - Diameter 88mm x 35mm with Nylon P Clamp D_29mm This ferrite magnet has aMagnetic Product Description: This rare earth pot magnet has a diameter of 88mm, a total height of 35mm with a nylon p clamp, and the closed loop is 22mm. This cable mount magnet has a pull force of 42kg. It is identified by the AMF magnet part number RCND88P.