Alvin SK450-6 smoke acrylic professional drafting triangle, drawing triangle. Quality INKING EDGE drafting triangle is constructed of molded 0.10" thick polystyrene plastic and features a transparent non-glare smoke tint for easy visibility. Edges are double-beveled with handy fingerlifts for quick placement and removal. Supplied in poly bag with hanging hole. Made in USA. Alvin 45/90 6" drafting triangle.