A long time ago, I bought a CPE with a tank and 4x5 reels and loader so that I could do E-6. It worked fine but eventually I put it away for many years. Now I want to use it as and economical way to process 4x5 B&W. I've used it a few times as such with dandy results. That's where my problems start. The thing came with a two reel tank with an inside dimension of about 4 1/2". I thought it would be nice to also have a single reel tank to process fewer sheets in less solution. Not knowing that they redesigned their tanks and reels in the meantime (Their site is OK for current products but has no info on their previous stuff). I bought a 2521 tank on ebay and was dissappointed to find that it was 5 1/2" inside diameter. I soon discovered that they had redesigned their reels. Apparently several times: 2509???... 2508???... 2518???... 2509N????... WTF is up with that??? So my option now are either to try to find a 4 1/2" single reel tank that will use my old reels or find a new reel that will fit my new tank. I have always used the loader but I'm sure that I could get away without one with a little bit of practice. I just don't want to keep buying random combinations of tanks and reels in the hope of eventually finding something compatable.