Yep, they're from Hosa. I'm not a fan of their signal cables, but they have some amazingly useful power adapters and cables and stuff. The little Y's made my racks much neater and made me much happier. If your local Guitar Center has any left in stock, they should be on clearance for about a buck each.
Hosa also makes a
NEMA 5-15 to IEC C13 adapter. If you're running a single amp, or powered speaker, whatever... You plug the little adapter into an appropriate length of extension cord, and bam, it's an IEC power cable. Awesome.
http://www.guitarcenter.com/Live-Wire-IEC-F--3-Prong-M--Powe r-Adapter-765449-i1166804.gc