Crazy strong magnets that can hold up even through felt! Offered in two sizes, extra tiny 1/4" x 1/16" and in larger 1/2" x 1/16". We love using E6000 for a permanent hold. Neodymium magnets are a type of rare earth magnet categorized at Grade N42 strength. Even though very strong they are brittle, use with care. Not for use by children. ISO certified.