In the interest of full disclosure, I do have a connection with W. Cooper.
Yes, W. Cooper makes filters for many others and sells their own under the Ranger brand. They are a small company that does little advertising so costs are lower and filters less expensive, but very good quality. Main difference is that the tanks are thicker and much heavier than most others, and the internal parts (hub and laterals) are larger that most others. Built much like a commercial sand filter. The company was started about 20 years ago by a gentleman named Wilf Cooper who helped create one of the first Sta-Rite sand filters. They are Canadian, but most are sold in the NE and SE USA.