Railway reserves the right to procure the material only from Proven Sources having satisfactory past performance for supplying the tendered item (Make: Escort / Knorr) to Railways. The tenderers must upload documents pertaining to their credential / past performance in Zonal Railway/PUS/Other Govt. Organization, i.e. copy of purchase order corresponding challan, inspection certificate & R/Note in support of the same to be uploaded. If firm failed to upload/attach the said documents then their offer will not be considered as a valid offer and summarily be ignored. No back reference on either side will be made or entertained in this regard.