Invisible Refill Ink: Convenient! Durable plastic case and long- lasting felt sponge inside! Last a long time! Invisible Refill Ink:This product can be sealed on all kinds of dry surfaces including: glass, paper, wood, plastic, and cloth ;invisible usually,but clearly show to wicket tellers, detectives, pawn shop owners and police when under the black light! It can also be used to stadiums, ...