Tracking Guides are placed on the tooth side of the timing belt. Guides are intended to improve tracking, to reduce wandering (side to side movement).
Tracking Guides generally include K6 [G6], K10 [G10] & K13 [G13], some special guides include K8 [G8], K12 [G12] & K15 [G15], while custom sizes (lengths, widths and heights) are available upon request.