METAL OUTER BOWL
This family of pipes have been seen as Knowles Air Lite (believed to be Canadian version), Roybrooke, Comet, Original Gridiron and the Greenwich House Thorokleen.
Seemingly sold in sets that comprised a normal briar bowl as well as the metal outer with a briar insert. The body of the pipe can be hexagonal, square ( Thoro Kleen only seen this shape) or circular in cross section. Regardless of variant all parts are interchangeable. The unmarked version tends to be regarded as the COMET, all the others being stamped with a name. See others on this site under their name
Centre image numbered as follows
1...Knowles Air Lite
2...Greenwich House Thorokleen
It appears that Alcoa (Aluminum Company of America) cast pipe bodies cetainly those used by Comet
There seems to be a selection of mouthpieces, some taking a filter. All come initially from the Greenwich House Corp, New York. Originally the Comet was available with the outer metal bowl and the polished briar bowl for $3.50 the set