Sahra Industrial Design
Thread Ruler
A protractor, compass and ruler combintion with a unique thread construction allowing you to draw elliptic figures, arcs, circles, angles and parallel lines.
The ruler that can draw elliptic figures.
An All-In-One Geometry Set
Thread Ruler TM
Thread Ruler-C
Compact model, ideal for math students, replacing old fashioned geometry box with one simple instrument.
(Ruler length 7.5 inch)
Ideal for school teachers demonstrating the construction of geometric figures on large marker boards.
(Ruler length 15 ½ inch)