... MM* Material, Acrlic&Aluminum, it is steady and have high accuracy* Have three scrow holes, it is easy to ... the other products* Precision is 45'+/-8', * Air bubble will be always at the middle of vial when put ... the vial on the level table. * The air bubble could be aggregated in 2 seconds after collision* The ... 4", and could do the other requests also) High quality aluminum alloy circular bubble vial