Cherne’s mechanical cleanout plugs make it simple to test a DWV system, the company explains. Available in 2", 3" or 4" configurations, these plugs are built for quick and easy mechanical operation. Each plug’s two-stage locking mechanism locks firmly in for both test and drain positions, allowing for high-pressure testing up to 150-ft.-head/65psi/15 floors (at 10-ft.-head per floor). Cherne.