Challenger O-Ring Replacement Kit Back Catalog number: 811-9913-01 Manufacturer: SENSIDYNE Availability: In the manufacturer's stock Price on request - + Recommended 800222 Tool Kit, LFS-113 Price on request FTK 3010-4023 Quantifit 2 Battery Pack Price on request 800843 Carrying Case, Hard Side, Deluxe (18" x 13" x 7"), Gilibrator-2 Price on request