PSMailers pressure seal documents are designed to fold, seal, and mail in much less time than conventional printing and mailing processes. Pressure seal checks are available in C Fold and are guaranteed to work with our pressure seal equipment. PSMailers checks offer a wide variety of security features to prevent fraud and are Check 21 compliant.• C Fold (Letter fold)• Paper size: 8.5” x 11”• Stock: 28# Security Paper• Check color: Basic White• Photocopy void pantograph• Heat sensitive ink