These magnets have screw bush hole,can for M3,M4,M5,M6,M8 M10 or customized.They need to fastened with an male thread or hook.As the metal pot to change the magnetic flux to make the force become strong,so even with a small size,but the force is very strong.They are suitable for strong and quickly removable fasten no need drilling.They widely use for trade fair,any shop build ,at home or other purpose.No matter use in private household or commercial or hobby applications are all suitable.