KFRD consists of two instruments FRD-A (sled 1) and FRD-B (sled 2). Instruments FRD-A and -B are two identical and independent position sensitive x-ray spectrometers.
Position Sensitive Detector System (PSDS) includes: a Multi-Wire Proportional Counter (MWPC); Pulse Processing System (PPS) includes front-end electronics, discriminators and pulse shaping amplifiers, produces control pulses; Secondary Power Supply and High Voltage Supply (SPS-HVS) provide necessary voltage for PSDS and PPS; Information Conversion System (ICS) transforms analog pulses into digital code; Data Processing System (DPS) forms arrays of scientific and housekeeping information suitable for transmitting via the onboard information system (BIUS), receives and decodes commands, clock and synchropulses coming to KFRD; Output Channels System (OCS) maintains link with BIUS and telemetry systems of the spacecraft (receives relay commands and transmits analog information).
| Detector MWPC | filled with 85%Xe+10%Ar+- 5%CO2 at pressure 1.3 atm |
| Energy band | 2 - 25 keV |
| Entrance window | 120 mm diameter |
| Window Thickness | 50  m Be |
| Efficiency/effective area | 0.98/1100 cm2 at E=5.9 keV |
| 0.44/ 35 cm2 at E=22.1 keV | |
| Energy resolution | 17% at E=5.9 keV |
| 9% at E=22.1 keV | |
| Spatial resolution | 0.5 mm at E=5.9 keV (10 arc sec in focal plane) |
| Angular resolution | 2 arc min (limited by mirrors) |
| Timing | 1/4096 ;
 sec |
| Dead time |  sec |