India has approached the US to help identify the Night Vision Device (NVD) used by the three terrorists involved in the Gurdaspur terror attack late last month. Besides the NVD, the Government has also sent a request seeking details of Global Positioning System (GPS), used by terrorists in reaching the police station at Dina Nagar where they were engaged by the Punjab Police and subsequently neutralised. The manufacturer of the device is based in the US, official sources said here on Monday.