The Sirchie Cocaine ID Swipes can presumptively identify cocaine from trace amounts of residue present on surfaces that have been in contact with cocaine. These 5" x 6" wipes are easy to use and results are immediate. Simply wipe the suspected surface with Cocaine ID Swipes and if cocaine is present, the swipe will turn blue. Swipes have an unlimited shelf life ensuring reliable results. Swipes come in boxes of 50 each.