1.multilayer screen/pipe base screen
2.material: 201 304 304L 306 316L
3.STC, LTC. BTC thread or welding
They consist of two screens or multilayer screen.
Perforated pipe inside and Johnson type screens outside.
The base pipe can be made of casing pipes, seamless pipe or welded pipe.
ID of Johnson type screen equals OD of the perforated pipe