4500 Tank Kit (Fill Nipple, (2) 7.5k Burst Disk, (2) 1.8k Disk, 100 Tank Orings) Includes Fill Nipple, (2) 7.5k Burst Disks, (2) 1.8k Burst Disks, (3) Bottle-to-Regulator O-Rings, (1) 100 Pack 90 Durometer Polyurethane Tank O-Rings