SB0850 Non Phthalate Velocity Blocker Grey is a low cure, press ready under base designed for 100 percent polyester and poly blend fabrics. It serves as a first down layer or barrier base that stops dye migration, keeps top colors bright, and improves overall print consistency. SB0850 offers exceptional migration resistance, fast fusion characteristics, and a noticeably soft hand that enhances the feel of the finished print.