Cov cwj mem taub hau siv roj{{0}} raws li cov cwj mem ballpoint feem ntau yog ua los ntawm cov hlau tsis muaj steel lossis cov khoom siv tawv tawv. Qhov loj ntawm txoj kab uas hla ntawm lub pob txiav txim siab qhov tuab ntawm cov kab ntawv sau. Cov pob kab uas hla yog 1 hli, 0.7 hli, thiab 0.5 hli (feem ntau yog qhia rau ntawm tus cwj mem lub cev lossis cov khoom siv ballpoint). Ballpoint cwj mem number case yog tsim tshwj xeeb, feem ntau yog tov nrog cov xim, hnyav thiab viscosity hloov kho. Cov xim zoo nkauj yog xiav, dub, thiab liab. Ordinary inks feem ntau yog siv rau kev sau ntawv, thiab cov inks tshwj xeeb feem ntau yog siv rau kev sau ntawv. Tus cwj mem siv rau kev sau cov ntaub ntawv feem ntau yog cim nrog lub cim ntawm qhov rov ua dua. Piv txwv li, cov khoom siv hauv tsev yog cim nrog lo lus DA.
Cov roj-raws li tus cwj mem yog thawj tiam ntawm ballpoint cwj mem series. Nws tau ntau dua 60 xyoo txij li nws tau muab tso rau hauv kev ua lag luam hauv cov khoom siv. Tom qab lub sij hawm ntev - txhim kho, cov roj- raws li tus cwj mem ballpoint muaj cov cuab yeej tsim khoom, cov khoom lag luam ruaj khov, lub neej ntev thiab kev sau ntawv ruaj khov. Tam sim no nws tau dhau los ua cov khoom lag luam ib txwm muaj ntau yam hauv cov khoom siv ballpoint cwj mem. Cov cwj mem siv rau hauv cov cwj mem oily ballpoint muaj viscosity siab, yog li kev sau ntawv kuj hnyav.
