SBBSPR System Sensor Red, Surf. Wall. Mount Back Box The SBBSPR System Sensor is red, wall-mount, compatible with SPR, SPRV, SPSR, SPSRH, SPSRV, SPSR-P, SPSRH-P, SPSRV-P. The SpectrAlert Advance SBBSPR is a red surface mount back box for wall installations.