The Tubex XL
The Tubex XL air rotary system utilizes a down the hole hammer with an eccentric bit to allow the casing to follow the borehole in the most difficult drilling conditions. Casing sizes range from 4", 6", 8" and 10" in diameter.
The Tubex XL is extremely effective in alluvial outwash, i.e. boulders, cobbles and large gravels. You might remember Tubex XL by it's prior name, "Odex" Casing Under Reamer.