TUSQ bridge pins come in two sizes or styles, Traditional Style, sized to fit Martin guitars, and Presentation Style, which fit most other guitars.   This guide is written for Traditional Style or Martin pins.    

Although Traditional Style pins are sized primarily for Martin guitars let me tell you how I check to see if the pins will work if I have any question here at the shop.  The most important measurement when sizing bridge pins is the diameter of the top of the shank, immediately below the collar beneath the pin head. Measure using an accurate ruler or calipers, to within .03 inches or .8 mm. Note that the overall length of the pin is inconsequential, as the pin is suspended in the hole by the top of the shank. The shank for these pins measure .2020in/5.14mm.

Traditional Style pins are available in both classic Martin black with white dot and classic Martin white with black dot or you may choose either color with inlay of Mother of Pearl or Paua.  The photo below is of black Traditional Martin TUSQ Style pins with Paua shell inlay.