This jet is identified by the numbers 723 being stamped on it. The 723 series are used in our HSR / TM42, 45 and 48mm carbs.
The lower the letter and number indicates the leaner the jet. Example Y-6 is leaner than Y-8. These are in 0.01mm increments and the 1/2 size 5’s are in a 0.005mm increments. Only the shown sizes are available.