Oval Metal Former Tube Post tension duct Code Name Size (mm) Length (M) 418720 Slab Duct 87 x 20 87 x 20 5.8 417020 Slab Duct 70 x 20 70 x 20 5.8 414320 Slab Duct 43 x 20 43 x 20 5.8 4120DM Single Strand Duct 20 Ø 20 5.8