STOP Signs- 18x18-3M Engineer Grade Prismatic Reflective Street Legal STOP Sign These Engineer Grade PrismaticSTOP Signs are constructed of rust-free, heavy gauge, durable aluminum STOP Signs are made using 3M Engineer Grade Prismatic (EGP) reflective sheeting and 3M inks only Engineer Grade Prismatic STOP Signs Guaranteed by 3M for 7 years of no-fade service STOP Signs have holes drilled at top and bottom center for easy mounting Our STOP signs meet Federal MUTCD R1-1 STOP Sign construction specifications.