PSI Fingerprints Peel 'N Place decoration gives you black fingerprints that you can place on windows, walls, and more. plastic decoration clings to most smooth surfaces without adhesives. PSI stands for Party Scene Investigation. Perfect for Halloween, murder mystery parties and other such occasions. Includes 22 fingerprint in assorted sizes. PSI Fingerprints Peel 'N Place measures 12"W x 17"H.