A multi-spindle automatic bar machine having a housing, a plurality of spindles, each with a collet at one end, and mounted with a rotating head which is carried by the housing, the rotating head being adapted to index the spindles through a plurality of tooling stations. A buffer layer is formed on the absorber layer, and a top transparent conductor layer is deposited over the buffer layer. The insulating barrier can be fixed to the housing of the service device. In one application, the multiplexer assigns a variable number of the upstream data links between the central office and the multiplexer on a dynamic, adaptive, and automatic basis to individual ones of the downstream data links. The retainer has a portion at least partially blocking the fluid flow area when the inflator is unactuated.