The Snowpulse cylinder is made from aluminum and should be filled with dry compressed air to 3000psi. The cylinder has a pressure gauge so you can see how full it is, or check for the unlikely event that it has leaked. You should always check the pressure gauge before you head out. The extra cylinder is great to have as a back-up on a long trip - in case you accidentally deploy your pack and you are nowhere near a refilling station.
These work for all Highmark/Snowpulse packs (made after 2015), all Mammut packs, all Dakine Packs, all Ortovox packs (made after 2018), all Jones packs and any other pack that uses the Snowpulse system.
Please note that full cylinders are the only exception to our "Free Shipping" offer. We charge $15 to ship full cylinders to cover the cost of the Dangerous Goods Shipping Charges that we incur.