This is our pocket sized Tiny T-Rule from Incra (TINYT03)
Measuring only 3" by 4.5". It offers Incra's patented marking holes at every 1/16th 32nd and 64th from 0 to 3 inches. It also has slotted height marking holes at every 32nd on the end. This size is so handy many of our customers keep it in their pocket anytime they are in the shop.