Torx wrenches and screws are used to secure parts in electronics, automobiles and bicycles. The screws are designed to hold the the contents more firmly in place than traditional screws, with less chance of being removed by traditional screwdrivers.
Torx wrenches vary in size with each size corresponding to a specific screw. The sizes range from a T1 wrench to a T100 wrench. Each wrench can only safely remove screws of one particular size.
The number and letter assigned to each wrench dictates the size of the star on the end of the wrench. The T10 wrench, for example, measure .107 inches across from one point to another. The T100 measures .871 inches across from one point to another.
Less common version of the Torx wrench is the E-Torx Wrench which goes around a corresponding screw instead of inside it as well as five point Torx wrenches.
As of November, 2010, Torx wrenches are available in hardware stores for an average cost of $10 for a set of 10 wrenches.