There is a lot of misinformation regarding the spirit line. The drums you have pictured are Niles badge, which are 3 ply, no re rings and a 45 degree cut. Those shells were in fact made by Slingerland. They are left over 3 ply Niles shells without re rings, often confused with the import spirits. Included in the spirit line are 6 and 9 ply mahogany kits, same pearl style mounting system etc. I recently had a set similar to this but a bit earlier, I can confirm that they were 3 ply, Niles badge with a s/n. There are also black interior versions which are 3 ply. Mahogany versions are obvious, the shells look like any other import 6 or 9 ply mahogany shell with a 45 degree cut. Look at the interiors of those drums, clearly not mahogany. The other giveaway, 10 lugs on the bd. Reference the catalogue, 8 lug bd, 9 ply mahogany, 80's version was 6 ply mahogany, those are the ones to avoid. The 3 ply versions are actually a great bargain, sound decent, all the confusion regarding the spirits continues to keep the prices low.