The original FL-910 released when the US Duratecs became available. Originally, it was exactly the same as the FL-400, however it was a little over an inch shorter. This is because the Duratec I4 engines have the oil filter placed straight up and down at the very bottom of the engine bay right behind the radiator. Any longer filter will be exposed to an impact...in fact, when the Duratecs first released, dealers were using the FL-400 filter without knowing any better, and there were incidents with curb strikes taking out the filter.
Anyways, at that time they were made by purolator. Fast forward a few years, and they redesigned the filter with the FL-910S name...it included a silicone anti-drainback valve. This was because the FL-400s had been discontinued, and the 910s was now its replacement...and on some cars, this included an upside down installed orientation. Additionally, the recommended OCI's grew longer, on the focus it went from 5000 to 7500.
Note...during the first few years, these filters were pretty much identical to the standard Purolator filter. Once they moved to the silicone ADBV, they seemed to have also switched to a threaded end bypass design. Originally it was a dome end bypass. However, these filters are still made by Purolater IIRC.
For a little over $4, its a great filter.