Roj hmab coated hlau nplaum yog qhwv ib txheej ntawm roj hmab rau sab nrauv ntawm cov hlau nplaum, uas feem ntau yog qhwv nrog sintered NdFeB hlau nplaum sab hauv, sib nqus ua hlau ntawv thiab roj hmab plhaub sab nraud. Lub plhaub roj hmab ruaj khov tuaj yeem ua kom cov hlau nplaum nyuaj, nkig thiab corrosive kom tsis txhob muaj kev puas tsuaj thiab corrosion. Nws yog tsim rau sab hauv tsev thiab sab nraum zoov magnetic fixation daim ntaub ntawv, xws li rau lub tsheb nto.