1. Kev kho deg ntawm swb rail: Qhov no tuaj yeem pom los ntawm qhov muag liab qab. Koj tsis tas yuav mloog ntau zaj dab neeg muag, koj tuaj yeem nkag siab nws ib txwm muaj.
2. Slide rail qauv thiab cov khoom siv: Saib ntawm qhov cross-sectional thickness ntawm cov khoom siv hlau ntawm cov swb rail thiab nws cov qauv, qhov zoo ntawm cov swb rail uas feem ntau siv ntau yam yas tsis zoo li tag nrho cov hlau swb.
3. Lub ntiajteb txawj nqus tshwj xeeb: feem ntau yog hais txog qhov hnyav ntawm tib qhov ntev lossis ntim chav tsev, ntawm no yog hais txog qhov hnyav ntawm tus swb rail ntawm tib hom (xws li ob txoj hlua).
4. Kev siv tau: sai li sai tau thaum koj ncab qhov qis qis, koj tuaj yeem hnov qhov hnyav, lub zog, thiab lwm yam.
Hloov kev lag luam thiab lus