a) Nrog pab tuav kom ruaj ntseg ntawm kev cob qhia txav
b) Nrog lub zog siab engineering yas barbell raj tiv thaiv npog.
c) Nrog limiting mechanism kom muaj kev nyab xeeb ntawm tus kws qhia.
d) Nrog rau ntau theem FOAM hloov kho, nws tuaj yeem hloov kho rau hauv cov ces kaum sib txawv kom tau raws li qhov xav tau ntawm cov neeg sib txawv.