These trammel points turn a standard yardstick (not included) into a compass. This is a particularly handy arrangement, as the distance from pin to lead can be read directly from the yardstick's calibrations.
They are made from solid aluminum with a milled slot that will fit 1" wide rulers. Adjustments are made simply by loosening the knurled nuts and sliding the points along the rule. The tightening sleeve is also knurled.
Use standard-size leads (one included).
Made in USA.