Liquid Vapor Piezometers can be used for site soil investigation, where underground storage tanks have been abandoned or removed. Available in 1/2" - 4" Specify Plug or Point. The 40 Micron Porous Polyethylene units may be screwed together for longer lengths or placed at various depths in the well. Adapters flush joint thread to NPT are available. All fittings sold separately: Flush thread male plugs, female flush thread caps or points.