FYI, there are 2 OXY-PRO is Calgary, , , the BEST one is OXY-PRO, 538 42Av SE, open sat till 1pm, best prices and will exchange competitors bottles, with some exceptions, , , check with them first. AVOID the store in the foothills, , , RULE OF THUMB- Air Liquide and others will NOT accept or refill competitors bottles, period. Be careful when buying bottles from KIJIJI cause you may not be able to get them filled by the bottle owner unless you have or set up an account, and you are out the coin u spent. KMS will only re-fill bottles, and not all peeps there are 'qualified' to do this.