I have this single ring coming to me from an ebay.uk win and I noticed an odd mark on the underside of the comb plate in the listing picture. If you look closely at the underside of the head, you can see what looks like a symbol with a square around it (on the left side of the head). Anyone see this before? I have single rings from this era without this mark and I haven't been able to dig up any info on mr-razor.