FAST SHIP!! PRIORITY MAIL (2-3 DAYS!) . You are purchasing 500 grams of Reagent (99.5+ min.%) Sodium Thiosulfate, Pentahydrate. This is NOT the cheaper quality large crystals others sell for dechlorination of pools, etc.. Buyer must be 21 years of age. Buyer assumes all liability for the use of this item. Buyer agrees to not hold the seller or Amazon liable for the use of this item. Buyer agrees to use this item in accordance with all local, state, and federal laws. This is for laboratory and scientific use only! NOT for food or drug use. Shipping will comply with all USPS regulations. Picture may not reflect new GHS labeling.