This formula of our synthetic ballistic gelatin is 100% clear, reusable, and requires no refrigeration! Our entire line of NATO synthetic ballistic gelatin follows the same protocol for traditional 10% ballistic gelatin. To pass this protocol a BB must meet the following criteria, which is by shooting a BB at 590 feet per second +/- 10 feet into a block of gelatin, and the resting position of the BB is (1.25”-1.75” or 4.4 ± 0.2 cm). All blocks in this category follow the NATO protocol for calibrating ordnance gelatin 240A so it can be used as ballistic gelatin. To pass this protocol a standard steel BB .177 caliber (4.5 mm) is shot from an air gun over a chronograph at 590 feet per second (fps), plus or minus +/- 10 feet, 10 feet away into a block of gelatin, and the resting position of the BB is 3.2 cm – 4.4cm (1.25 inches to 1.75 inches The key difference between NATO & FBI calibrated gelatin is density. NATO gelatin is a 20% solution and FBI is 10% solution. NATO ballistic gelatin must be harder because they only use full metal jacket bullets, FMJ. All of our Clear Ballistic Gelatin blocks replace standard 240A ordnance gelatin. * 100% crystal clear * Contains NO gelatin powder * Odorless * Replaces standard ordnance gelatin * Completely Reusable * Only cost effective ballistic testing medium * Multiple shots per block * Mimics human tissue 100% * No refrigeration required * No Mixing * No Cooking * Meet the FBI & NATO Protocols for ballistic gelatin testing * Durable—just rinse with water