Appendix II, 2a states that:
| The shaft of the club must be straight from the top of the grip to a point not more than 5 inches (127mm) above the sole, measured from the point where the shaft ceases to be straight along the axis of thebent part of the shaft and the neck and/or socket.
This Rule implies that the shaft must extend to the end of the grip, or at least that the grip should not extend beyond the top end of the shaft more than is necessary to accommodate the butt cap (see Figure 10).
Fig. 10 - Illustrations of "butt caps"
The "5-inch" measurement should be made using a pair of callipers (to measure the depth of the head at the point where the shaft is attached) and a flexible measuring tape, or a piece of string (to measure the length of any bend or bends in the shaft from the point where the shaft ceases to be straight) (see Figure 11). The point where the shaft ceases to be straight can be determined by placing a rigid steel ruler along the straight part of the shaft and marking the point where the shaft and the ruler are no longer in contact. It would not be possible to measure a bend in a shaft accurately using a normal, stiff ruler. This Rule is particularly relevant to putters where the shaft is inserted directly into the head. (For putter heads that have a "neck" – see Section 6 - Attachment to Clubhead).
Fig. 11 - Measuring shaft straightness