This pack includes two large, transparent triangle rulers, essential for school and work. One ruler is a 12-inch 30/60 degree set square, and the other is a 9-inch 45/90 degree set square. Both rulers feature a CM scale for precise measurements. They are made from high-quality acrylic, offering excellent optical clarity and transparency. Acrylic is also highly impact-resistant, being up to 17 times more resistant than ordinary glass, and is half the weight of glass. The rulers are precisely machined for accurate use.