Bosch makes the rails for Mafell AFAIK. It makes sense if you consider how large Bosch is and the limited facilities of the Mafell factory. Bosch licensed them to Mafell who at the time were the only brand using them. Bosch has since used the FSN rail system for a number of years after migrating from an older rail system which kind of looks like Festool. Bosch has a lot of subsidiary brands that can churn out things for them with the Bosch logo.
Which factory makes them? Dunno - I am pretty sure it ain't Mafell. But they look sexy in red.
I did think the rails were from Mafell but was told by a Bosch rep at a trade fair that it was a Bosch patent for sure and they licensed it to Mafell. Neither Bosch nor Mafell were at the time very good at marketing their brands. Bosch has since grown to be quite a large player on our (small-ish) market.
The rails are not hard to cut down to size - I much prefer the 1600 rails over the 1400 rails from Festool and others. With two of the 1600 I can cut any length board available here with some room to spare. (boards are usually up to 3050mm) With Festool I would fall short of the target with two 1400mm rails.
There are a few boards that are 3660/3665mm but 2x1600 and a 800 or my 3000+800 takes care of that.
Festool would still come up short with the 1400+1400+800...
If you are not happy with the 1600 you can cut it down to that magical size that is perfect for your needs.
With one 1600 mm I can do crosscuts on most sizes.
The one niggle I have is that I have the 800mm rail which I use frequently and with the 1600 that makes a 2400mm rail. That is too short as most boards here are 2440mm - and you want some overhang with the rails.
I have solved this with adding the angle unit/short rail which is always connected to one 800mm rail.
Then I was approached by a vendor that had a bunch of surplus rails from several shops... ...I made him a lowball offer which was accepted since they don't want to dedicate a shelf to surplus gear so I got me a FSN 1100 rail and a FSN 3000mm rail - the latter used quite a lot as it strips down a normal sized board.
I also got clamps, quick clamps extra rubber strips, connectors and two FSN angle units. All for 1/6th of original price!!! I did not need some of the stuff but since it was a take it or leave it deal I wasn't going to haggle on a give away price anyway!
The FSN 1100rail was of course a great match to the 1600mm giving a 2700mm duo that tackles some boards that are 2500mm, with ease. With the angle unit I would say the 1100mm is perfect for cutting down 1220mm wide boards (not length wise though):
The 3000mm rail is always in the shop. Only took it out once to trim down a deck - but it did save the day, and the day after too.
Mysetup is:
KSS40 0ne Mafell 800mm rail and WAN angle unit to complement the Flexirail 1400 and the short rail.
MT55cc Mafell WAN rail 2 x 1600mm rails, one 800mm rail.
Bosch/Festool Routers w rail adapter: Bosch FSN WAN, 800mm holy rail, 1100mm rail, 1600mm holy rail. 3000mm rail.
All rails see some frequent use except for the second 1600mm rail on the MT55cc.
The Bosch /Mafell FSN WAN does help out with some shortcomings (pun intended) and is square enough when attached to the other rails thanks to the superior connectors.
All in all the FSN rail system is clearly better than the Festool track system. I surely don't miss the Festool rails.
The size increments on the FSN system is very clever and covers all bases for me. I did cut down one FSN rail for a specific repeat use once but I can't remember for what. Might have been subflooring at an angle where a 800mm would have had not have had enough to place the saw at depth of cut outside the board and run through. Did not have the 1100mm board back then - or the FSN WAN wide angle unit which would have been absolutely perfect with the 800mm rail. If I was doing a lot of subflooring I would have "permanently" attached a WAN rail to one 800mm rail and then cut down the 800mm rail to whatever size would cover the longest diagonal/angle.