Symmetrical, modular blocks each having a plurality of fixed, equally spaced, gauging elements, namely loopers, needles, and reeds protruding therefrom, the blocks are positioned on the sides of the guide bars of a
tufting machine, each guide bar having transverse channels at equally spaced intervals. These channels respectively receive guide bars of the blocks when the blocks are removably positioned on the sides of the guide bar. Bolts or screws secure the blocks in place on their guide bars so that their needles, loopers, and reeds are appropriately gauged and positioned for
tufting action, protruding toward the
tufting zone.