HUSQVARNA MULCHING BLADE FOR MODELS BIOCLIP 90 , RIDER 11 BIO , RIDER 13 BIO , RIDER 14 BIO , RIDER 15 BIO , RIDER 152 V2 AWD , RIDER 16 , RIDER 16C , RIDER 155 , RIDER PRO 18 MODEL - TECHNICAL SPECIFICATIONS LENGTH 481 mm MIDDLE HOLE 24 mm OUTSIDE HOLE 8. 1 mm CENTRAL HOLE INDEX 48 mm CODE: 13271039 ORIGINAL CODE : 506 96 97-10 , 506 96 97-01 531 00 75 -25 SR