The ST 89 is a set of indexable carbide lathe cutting tools. 5 tool holders are included in the set including the E style for general turning and threading. AR and BR styles for cutting right to left and shoulders and AL and BL for cutting left to right and shoulders. Also included are 5 triangular carbide tips ( ST 89 A ) giving you 15 cutting tips in all. An allen wrench and several spare allen bolts are included in the fitted case. These holders are specially selected to fit the SHOPMASTER toolpost and will last a lifetime. If a tip is dulled or chipped, you can rotate the triangle without having to re- set up your work. The tips are standard TCMT styles used worldwide and available in many supply houses.