O2 cylinder wrench is small a device used open and close the O2 tank.
The wrench is attached to a PVC strap which should be attached to the post of the tank to reduce the risk of misplacing.

The O2 Airway Kit contains 425L of oxygen and is designed for any environment in which a patient may unexpectedly experience a medical emergency where oxygen is needed. Extra equipment must also be onsite to deal with the emergency efficiently. The job of an O2 Airway Kit is to contain both the oxygen and the equipment required to treat a patient for the first thirty minutes or so of a medical emergency.

Each O2 Airway Kit includes:

1 x D size Cylinder 15.0 cu.ft / 425 litre - OXYGEN
1 x Clamshell Carrying Bag
8 x Airways (40-110mm in Polybag)
1 x Disposable Adult BVM
1 x 0-15 LPM Adjustable Regulator
1 x Wrench
1 x Adult High Concentration Mask With Tubing
1 x Pediatric High Concentration Mask With Tubing
1 x Adult Nasal Cannula
1 x Pediatric Nasal Cannula
2 x Pairs of Latex Gloves
1 x Surgitube Tubular Gauze
1 x CPR Kit
1 x MDI Spacer
1 x Pocket Vent Mask With Oxygen Connector

This D sized oxygen cylinder features a toggle valve with a regulator connector.