Invisible number case
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Pob tshab Invisible Ink nrog Fluorescent cwj mem duav rau cov phau ntawv zais cia tsis pub lwm tus paub
Cov khoom muag muag muag cwj mem kua mem kua mem kua txiv, 18 ml tsis tau-carbon ua khawv koob ink UV teeb fluorescent number case, zais cia cov mem kua, khoom plig. Tsis-carbon Khawv Ntsig Invisible Ink Invisible Ink tsuas yog pom nyob rau hauv kev thaj chaw ntawm lub teeb cdaviolet. Cov ntsiab lus sau nyob rau hauv number case yuav ua rau pom nyob hauv qab ultraviolet teeb. Xyuas kom cov ntaub ntawv rhiab tsis muaj qhov tsis pom los ntawm kev ntsuas lub qhov muag nrog cov cwj mem tsis pom no. Cov lus sau nrog tus cwj mem no tsuas yog ua tau pom ib zaug lawv yog illuminat ...