Ntawv khob lub rooj hais lus qauv
(1) Kev co: cov ntawv nruas, lub suab coil, nruab nrab ntawm daim (elastic yoj)
(2) Cov hlau nplaum sib nqus cov txheej txheem: cov hlau nplaum, tus quab (T hlau), hlau nplaum conductive phaj (Hua Si)
(3) Lub tshuab khiav haujlwm, suav nrog cov phiab sib txuas, cov davhlau ya nyob twg, cov xov hlau, cov kaus mom thiab cov plua tshauv.