John, all you get in the ad is 2 pictures of 2 tubes (both pictures have the tubes laying on a table facing opposite directions, and you see both tubes laying together from either direction). One is a push in, the other is a 1/4 turn in. Peoples comments tell you only get one tube, but the ad doesn't tell you that you only get one, or which tube you get. The Summit site, in the comments, (the only place you find out you only get one tube) someone asked which tube, and someone else asked what the diameter was. That was where they stated it was at 1/4 turn lock in one and it was 1.75" in diameter. Summit is the only place that offers any info available on them that I've seen online. Apparently, everyone selling the extension tubes are all selling the same MR Gasket tubes, because everyone has the same pictures and pretty much the same price.