Ideal for hundreds of uses, this unique protractor allows you to measure, mark and transfer any angle...inside, outside, barred angle and slope angle...under 90 degrees or over 90 degrees. It's ideal for fitting dollhouse siding to roof angles, setting table saw and disk sander angles, gauging model railroad slopes, measuring ship model mast rake angles, model airplane dihedral and more. Made of high impact plastic with knurled brass locking nut. Longest blade is 6 inches long. A winner of Switzerland's Gold Award for new inventions. Instructions included.