No more licking envelopes or stamps that can leave a bad taste in your mouth and not stick thoroughly. Universal® Envelope Moistener eliminates the need to lick envelopes by gently wetting the desired material to activate the adhesive. Save time and effort required to do a mass mailing. Constructed with a long-lasting polyurethane sponge that distributes moisture evenly without over-wetting. Use with water. Sponge Cup Moistener—Shatterproof clear plastic cup with long-lasting sponge. Moistener Size: 3" Diameter; Color(s): Clear; Material(s): Plastic/Foam (Water-Fillable).