1. Raws li tus ntoo khaub lig-section duab, muaj puag ncig (xaim txoj kab uas hla 5-9mm) thiab duab plaub (16mmx7mm, 12mmx2mm) thiab lwm yam;
2. Raws li hom hmoov core, muaj ib qho, sib xyaw, ntau yam sib xyaw thiab lwm yam;
3. Raws li kev faib tawm ntawm txoj kev tawm ntawm txoj kab, muaj hom sab nraud thiab sab hauv;
4. Raws li kev faib tawm ntawm txoj kev tsim, muaj cov ceg tawv, hom vuam thiab tom hom;
5. Raws li cov khoom tseem ceeb hauv lub xeev faib, muaj xoob thiab tag nrho (hmoov extrusion).
