An obturating assembly includes a body having an aperture for passage to the pipe of a fuel supply spout of predetermined outer diameter and an obturator that is moveable with respect to the body. 04 at 633 nm, and optionally at least one skin layer. The transmission of the data frames is effected with a defined timing relationship between the sub-networks. The reverse auction request for transportation or delivery is transmitted. Group TDMA provides increased throughput capacity as it provides a balance between scheduled access and pure random access. Each L-shaped portion comprises a first spacer in a plane parallel to the tabs and a second spacer having a depth essentially equivalent to a distance between the mounting surface of the wall studs and a finished wall surface in a fourth plane parallel to the jamb.