The probes were housed within modified photon torpedo casings and had a range of 7.6x102 light years. They were powered by a matter/antimatter warp field sustainer engine which could propel them at warp 9 for 12 hours or warp 8 for 14 days. In addition to standard sensors the probes could be fitted with mission specific modules. (TNG reference: Star Trek: The Next Generation Technical Manual)