Complex sentence: A variant of the SFR-39, the SRF-39FP, has a transparent exterior designed to thwart contraband concealment, and the radio accordingly often appears on the commissary lists of U.S. federal prisons, hence the "FP" suffix.
Split into simpler sentences: A variant of the SRF-39, the SRF-39FP, has a transparent case, designed to thwart contraband concealment. The radio often appears on the commissary lists of U.S. federal prisons, hence the "FP" suffix.