supply and maintenance of 4g based gps tracking devices along with sim card recharge and tr acking for a period of 30 months as per railway board guidelines vide rly board letter no ; 2017/track-i/29/8, d t. 16.01.2018. [ warranty period: 30 months after the date of delivery ] ] , amc of 300 nos 4g gps based tracking devices along with sim card recharge and tracking fo r a period of 24 months after expiry of warranty period of 30 months (ie. after supply and maintenance of 4g bas ed gps tracking devices along with sim card recharge and tracking for a period of 30 months vide srl. no.2) [ warranty period: 24 months after the date of delivery ] ]