plastic, coloured hollowed channels, imprinted graduation
engineer DIN = 1:2.5/5/10/20/50/100architect 1 = 1:20/25/50/75/100/125architect 4 = 1:100/200/250/300/400/500vocational school 2 = 1:20/25/33.33/50/75/100survey 6 = 1:500/1000/1250/1500/2000/2500