Our durable, reusable two-canister Soda Sense Exchange Box is your ticket to endless bubbles. Use our Box to mail us your empty 60L canisters (our canisters or their canisters, whatever, we’re not picky) and— hey, presto! — we will cheerfully return them to you expertly refilled for only $20.99 per refill, per canister — and always with free shipping!