This product is a game changer! Two rulers designed to speed up your half square triangle production. Use the rulers to trim before opening up the triangles and you get all four sides at once and even trim off the dog ears in the process. Works for 1.5″ to 6.5″ pieces. Excellent instructions are included. Once you’ve mastered the basic half square triangle (which takes about 5 minutes!) you can move on to quarter square triangles, 3 piece triangles and triangles with diagonal strips. Very versatile tool. Pair it with the Clearly Perfect Angles sheet and you’ll be whipping out triangles at mass production levels!