No marks of any kind on the bong........but at 13 inches, it's perfect. It holds alot of water. I bought it cheap off of Ebay, just wanted something quick and painless. I've literally spent $300-$400 on some bongs I've bought, I like the beaker ones since they hold a lot of water. This is EASILY the best bong I've bought for the money, and I'm thinking there must be a glut in the market. I live rural MD, farm land basically, and there's literally 3 head shops within 1.5 miles of me. One is owned by an old Indian guy (from India, not U.S.), the other 2 by youngsters who think they are businessmen. Lol
I hesitate to mention just 2 weeks ago I bought a bong, with a silicone base and top and a perc in the middle. Cost me $25 or so, used it for a day, then threw it in the trash. And my alcoholic neighbor buddy, gave me a brand new 8 incher (bong, not what Max is thinking) but it doesn't hold enough water to do shit. I'll clean it up and give it back.
And if you do not know what Rez Block concentrate is, look it up. A few drops in the bowl and your bong stays nice and clean, so you barely have to clean it. I think it's fruit pectin or something, but it works like a miracle.