What track cleaning fluid should I use?
This detailed article by Joe Fugate in the May 2019 issue of Model Railroad Hobbyist Magazine
will answer all your questions:
Why are there different models for N, HO and S?
When Centerline Products first started we only offered the cast brass rail cleaners with "pointed ends", these were not designed to NMRA specs for width.
The NMRA spec cars were the second models we developed for N and HO. The cars are narrowerhey were originally die-cast zinc painted black. You could kit bash a boxcar to cover one of these if you would like to disguise it.
In 2015 we purchased a HAAS VF2 CNC mill. At that point we started to machine the NMRA spec bodies from A360 brass bar.
This purchase allowed us to made all of our track cleaners in brass at a similar production cost. An added value for the customer as compared to the original die-cast. But now that they are all brass there is some confusion... "Which works better?" is a question we are often asked. They all will clean the same. But, some customers prefer one over the other.