729 (First number in the series) = The length of the belt in millimeters.17.7 (Second number in the series) = The width of the belt in millimeters.30 (Third number in the series) = The angle of the teeth on the belt. （SKU89244，Belt 723-18-30 ）and (SKU:80078, Belt 729 17.7 30) is universal can either fit same model of bike. This is the standard replacement belt for the GY6 50cc 139QMB 4-stroke long case engine, sometimes known as 729-18-30. These are used on Baja, JMstar, Jonway, Lance, NST, Peace, Roketa, Sunl, Tank, TNG, Vento, VIP and many others. Note: Scooters with a long case usually have a 12" - 16" rear wheel. Also fits below bikes,HONDA 23100-GW3-018 730X18.00 KYMCO ZX50 FEVER 23100-KCX-900 730X18.00KYMCO 50 Agility 4T(05/>) 23100-KEB7-9000KYMCO 50Bet&Win/Euro 2(02/>) 23100-KEB7-9000KYMCO 50Dink/LC/Classic Euro2(99/>) 23100-KEB7-9000KYMCO 50People/Euro2(99/04) 23100-KEB7-9000KYMCO 50People S(05/>) 23100-KEB7-9000KYMCO 50Super-9/Sport Euro2(00/>) 23100-KEB7-9000KYMCO 50Topboy(97/>) 23100-KEB7-9000KYMCO 50Vitality 2T/4T(04/>) 23100-KEB7-9000KYMCO 50Yup/Euro 2(02/>) 23100-KEB7-9000 supported the Brands of BAOTIAN, BASHAN, BENZHOU, CFMOTOR, CHARMING, DAYANG, DINLI, FUXIN, GEELY, GILERA, HANGLONG, HAOJIN, HAOJUE, HISUN, HONGZHOU, HUATIAN, JIAJUE, JIANSHE, JINLUN, JMSTAR, JONWAY, KAITONG, KEEWAY, KINROAD, KYMCO, LIFAN, LINGBEN, LINGTIAN, LINHAI, LINTEX, LONCIN, LONGJIA, MAWI, MEIDUO, MOTORRO, PIAGGIO, QINGQI, RHON, RIEJU, SACHS, SHINERAY, SKYGO, SUKIDA, TAOTAO, VESPA, VONROAD, WANGYE, WONJAN, XINGYUE, XINLING, XINTIAN, YIBEN, YINGANG, ZHONGYU, ZNEN, ZONGSHEN, etc.