The magnets in the HO cars can broadly be separated into three groups: Ceramic, Polymer and NdFeB (''Neo''). The Polymer magnets consist of amounts of Neo in a polymer block the same shape as the magnet aperture, and there are several ways to form those, which is where it gets 'interesting'.
The Neo magnets are differentiated in terms of strength (or, more accurately, potential energy) with an N prefix, N52 being the strongest (for comparison the traction magnets in a Mega-G are N30). The N measurement directly relates to megagauss-oersteds, which is why you see people talking of gaussing magnets when they want to measure strength.
The ceramic magnets in the cars are stronger than your average fridge jobbie. Tyco magnets are C8, and coupled with being large and anisotropic (directional) this enables them to perform as well as they do.
Polymer magnets are also measured in different ways, with different prefixes, but for truly surreal reasons. Due to long standing bad blood between the three US manufacturers of 'hobby' chassis, Slottech, Wizzard and BSRT, the polymer magnet has been used by them all as a political football.
For a while all three used an L prefix (to denote a level, an amount of Neo in the block), but some of the magnets with the same L rating were more equal than others shall we say. There was then a war with the amount of Neo going up and up, L25 being the ultimate. Nowadays the L prefix is less commonly used, and the method by which the blocks are formed keeps changing, all in the name of perpetuating what they have over there, a poisonous situation where all three manufacturers have their 'camps'.
