I got tired of dragging the air hose across the floor to power up the safety locks on my HD-9ST. I couldn't see paying $200 for such a simple device as the air bottle. I built my own using bits and pieces I picked up at the local plumbing supplier and McMaster. The bottle is 2" x 12" with end caps drilled tapped and fitted. The check valves, push-to-connect tubing connectors, popoff valve and mini pressure gauge came from McMaster. The 1/4" double end fittings, 1/8 to 1/4 adapter and 1/8" Tee came from a small local business, American Maintenance Suppliers. The mounting bracket is a coil bracket I had lying around in a bin. Total cost was right around $100 including shipping and petrol. The lift came with plenty of extra 6mm tubing but I only needed 12" to install the bottle. The initial charge comes from attaching a air hose to the quick-disconnect. Pictures speak volumes.