25254mm GPS L2 Ceramic Patch Antenna

It looks like you're asking about a GPS/GLONASS PCB active patch antenna designed to work on the L1 and L2 frequency bands. Let me break this down for you:
1. GPS and GLONASS:

GPS (Global Positioning System) is the satellite-based navigation system used by the United States, operating on several frequencies including L1 (1575.42 MHz) and L2 (1227.60 MHz).

GLONASS is the Russian equivalent of GPS, also operating on L1 (1602 MHz) and L2 (1246 MHz) frequencies.