The sticker under the seat of the lawnmower should have 102 on it, this indicates a 102cm / 40" cutting deck

Mower Deck suitable for e.g. the following device(s): CASTEL GARDEN Lawn Tractor(s): CG 14,5/102, CG 14,5/102 HYDRO, CT 13 5/102, CT 13 5/102 BLEUE, CT 13 5/102 H, CT 16/102 HH, CT 16/102 K, CT 17 5/102, CT 17 5/102 H, CT 17 5/102 H BLEUE, CT 17/102, CT 18 5/102 H BLEUE, CT 18/102 KH, CT 20/102 H, CT 20/102 KH, EB 12/102, EB 15/102 H, ET 13 5/102, ET 13/102, ET 15/102 H, ET 16/102 H, ET 17/102 H, ET 20/102 H, EUB 15/102 HYDRO, GT 12 5/102, GT 14 5/102 H, GT 15 5/102, GT 15/102 H, GT 16/102 H, TC 12 5/102, TC 12,5/102, TC 13 5/102, TC 14 5/102, TC 14 5/102 H, TC 15 5/102, TC 15 5/102 H, TC 16/102 H, TC 16/102 HYDRO, TC 17 5/102 H, TC 18/102 H, TC 18/102 H + M, TC 18/102 H + MULCHING, TCP 13,5/102, TCP 16/102, TCP 16/102 HY/EMC, TCP 18/102, TP 13 5/102, TP 13 5/102 H, TP 13 5/102 H - BLUE, TP 13 5/102 H - RED, TP 13 5/102 HYDRO, TP 15 5/102 H, TP 15 5/102 H+M, TP 15/102, TP 15/102 H, TP 16 5/102 H, TP 16/102 HH, TP 16/102 HH+M, TP 16/102 K, TP 17 5/102, TP 17 5/102 H, TP 17 5/102H+M, TP 17/102, TP 17/102 H, TP 18 5/102 H, TP 18/102 H, TP 18/102 KH, TP 20/102 H, TP 20/102 HYDRO, TP 20/102 KH, XT 140, XT 140 HD, XT 150, XT 150 HD, XT 160, XT 160 HD, XT 165 HD, XT 165 HDE, XT 165HD-HT 160H, XT 170, XT 170 HD, XT 180 HD, XT 180 HDE, XT 185 HD, XT 190 HD, XT 190 HDE, XT 200 HD CASTEL GARDEN 299911212/04-(2004) CASTEL GARDEN 299911212/06-(2006) CASTEL GARDEN 299911213/02-(2003) CASTEL GARDEN 299911213/UK6-(2006) CASTEL GARDEN 299911223/04-(2004) CASTEL GARDEN 299911223/06-(2006) CASTEL GARDEN 299911223/PF6-(2006)