VEXpro ThunderHex Stock - VEXpro 217-4017, VEXpro ThunderHex Stock works in all applications where 3/8in. or 1/2in. hex shaft will work, and also has rounded corners. These rounded corners allow the shaft to pilot inside a 10.25 or 13.75mm round (ThunderHex) bearing instead of a standard 1/2in. hex bearing. This eliminates some difficult manufacturing tolerances and results in a MUCH smoother end result. Simply put, ThunderHex bearings are the best way to create smooth-running hex shafts, and ThunderHex Stock helps you accomplish this without a lathe.Also, since you\'re essentially putting a round peg in a round hole, there\'s less struggling to align the hex of your shaft with the hex hole of your bearing.All ThunderHex Stock also includes a subtle but very useful feature: a 0.201in. hole through the centre. This hole provides a clearance fit for a #10 bolt or can be tapped for 1/4-20 bolts. This means that you no longer need a precision lathe to create custom-length, high-strength standoffs; simply cut the ThunderHex shaft to size and tap it with a 1/4-20 (or 1/4-28) thread. VEXpro 217-4017 1/2\" Hex x 0.201\" ID ThunderHex Stock 36\" Long