The holes are located on the inside part of the chair frame as shown in Pic. 1
Place tape measure in the middle of the strap. If it measures between 1 1/4” to 1 1/2”, order 1 1/2” strap. If it measures between 1 3/4” to 2”, order 2” strap. As shown in Pic. 2
Place tape measure on the outside part of the frame (left side) and measure across to the outside part of the frame to the right side as shown in Pic.3