Zento Gel Pen Uni Ball ZENTO Water-based Ballpoint Pen Refill 3 Colors, UBRZ Wasserbasis Kugelschreibermine Product Type: Pen Refill, Model: UBRZ, Material: Plastic, MPN: UBR-Z-05, UBR-Z-38 The Uniball ZENTO UBR-Z-38 refill is designed to transform daily writing into an effortlessly fluid experience. Developed with a next-generation water-based ink, it features POA surfactants, a special lubricant that reduces friction by 40%, allowing the tip to glide across the side with ease