Top cap for Thomson X2 and X4 1 18 Inch threadless stems when no spacer is used above the stem. May also be used with Elite stems. Triple Thomson logo not to be confused with the discontinued double Thomson logo stem top cap which will not work with an X2 or X4 stem. Beautifully CNC machined like all of Thomson’s fine stems and seatposts. Black or Silver. 6 grams.