Everybody who starts diving into such amazing hobby as rod building usually faces some problems with understanding those damn abbreviations that rod guides' manufacturers supply in their catalogs. Below is short guide to basic understanding what the information is hidden in all those letter/digit combinations, based on the data provided by Fuji Kogyo Co., LTD, probably the most worldwide-known manufacturer of rod components.
Prefixes. In fact, Fuji uses any of them in only one case, for the guides with the frames made of titanium alloys. And there are only two options, T- and T2-. The second is applied for the frames slightly darker in color than more "classical looking" T-. For example: T-KTSG6 and T2-KTSG6
As to a guide' abbreviation itself, first one or two letters usually correspond to frame color: B - black, IG - gold, P - polished etc. But there are two exceptions when frame color' is not mentioned at all:
One to three letters after those showing frame's color go for the guide frame' type (and Fuji produces many of them). Just some examples:
Note that sometimes those letters may tell a little bit more about guides' frame than you can expect:
...and so on.
After the letters that go for the frame type, there is one (always one) letter for the material of the guide's ring:
And finally, the last letter before digits showing guide's ring size is for the type of a guide itself. And, like with T-/T2- prefixes, there are only two possible options, G - guide and T - tip-top. In the last case, inner diameter of tip-top tube in millimeters is also added after ring size' digits (T-MNST 6-1.8)
And the very last one thing: the letter sometimes added right after ring size' digits. In the most cases, it corresponds to relative height of a guide within one frame type' lineup (if any applicable): L - Low, M - Medium, H - High. But there also may be other. For example, letter F goes for a flanged type of a guide ring/insert (T-KGTT 5F-1.6)