... one by one.it can be installed on becycle bike,mountain bike cell,toy bike,even motorbike,etc.It is very easy to install ... a ploy bag Packagepcs/CTNNW/GW(KG)MEAS(CM)300pcs3006/739×29×25500pcs50010/1149×39×22Custom HS code: 871499000Be passed Chinese CIQ ... -1993<>,below is certificate: sell aluminium alloy color bicycle bell mountain bike cell,mini flick bell