For anyone using these tanks having rotation problems (hanging-up when you change from CW to CCW), check to see if the bottom rollers on the reels are all touching evenly on a smooth surface. I needed to bend the support arms for the rollers very slightly (up or down) to prevent the reel from "rocking" to one side. Now both of the sets I purchased turn very smoothly. The first batch of twenty negatives (4x5) are as perfect, from a development point, as I can see. I am very pleased with this product and Liu's correspondence with me on some questions I had for him.