Single size underground Test-Ball® plugs are made of natural rubber material for excellent expansion and memory|Seals both round and out-of-round pipe|Removable inflation valve can be replaced if damaged or replaced with quick disconnect fitting|Features an eyebolt for use with a poly-lift line|Use to block flow or as a back plug for sewer air testing|Holds 40 ft of head and back pressure to 17 psi|Natural rubber body provides excellent expansion and a great seal in round and out-of-round pipe|Inflatable design can fit through test tees, sanitary tees, floor drains and other hard to access pipe openings|Ideal for testing DWV plumbing systems at pressures upto 13 psi or with 30 ft of head pressure|Utilizes a standard tire air fitting for easy connections