Portable oxygen and respirators may accompany you on Boston Express. A maximum of four (4) canisters may travel with the customer: Two (2) aboard the bus and two (2) in the baggage compartment. The maximum dimension for each container may not exceed 4.5 inches in diameter and 26 inches in length. Customers are responsible for ensuring that they have enough oxygen to complete their travel and are responsible for making arrangements for refills while en route. Oxygen canisters to be stored in the baggage compartment must be in protective cases with safety caps on the valves. Reminder: Always keep your medicine with you. Do not leave it in your checked baggage.