GLFG - Finger Guards, Protect your fingers while cutting with all your acrylic rulers. Made of Polycardbonate, 25 times Stronger than Acrylic Easy to Attach - Easy to Remove. So you're not stuck using them on just one ruler. 1/2" high protective barriers attach firmly to any acrylic ruler with three strong suction cups. Use one on a 12" long ruler, two on a 12.5" square or a 24" long ruler. Please go to www.Guidelines4Quilting.com for more detailed instructions.