Red hard rubber pens are much less common than mottled, so there is good reason to take care to use the correct terminology when describing such items. Red hard rubber, normally abbreviated "RHR", is a solid, opaque, orange-red, though it was also less commonly made in a browner shade like terracotta. Mottled hard rubber, normally abbreviated "MHR", consists of a mix of red and black hard rubber, usually more or less irregularly patterned.
Note that many use the abbreviation "RMHR", for "red mottled hard rubber". I do not, which has undoubtedly bettered the environment by conserving hundreds of "R"s over the years. In fact, my real objection to the additional "R" is redundancy: mottled hard rubber is for all intents always red and black, so the color really does not need to be specified, and if one were to specify it, why not go whole hog and use "RBMHR", specifying both the red and the black?
OK, there are mottled rubbers using tan and black and green and black and a few others, but they are incredibly rare -- so rare that the material would be central to the description, obviating the need for an abbreviation. And the most common non-red, non-black, hard rubber pens -- the Waterman colored Ripples -- are normally similarly described quite prominently by their color names and as Ripples, again obviating the need for abbreviations.
Anyway, abbreviate as you see fit, as long as it's clear -- but please don't call mottled hard rubber red hard rubber!








