1/2 pint or .25L means total interior volume of canister. Because liquid ingredients require ample space to aerate into whipped cream, we recommend using no more than 4 oz of liquid ingredients (fill only 1/2 full). Rubberized coating on aluminum with acrylic head. Easy cleanup. Makes fresh fluffy creams and mousses without the use of preservatives or stabilizers. Creams stored refrigerated in the dispenser will last for up to two weeks. Cream chargers are sold separately. Please note: Repeated discharging of N2O chargers may freeze the silicon seal surrounding the piercing pin and cause it to crack and leak gas. This abuse of product will void the return policy.