Analyst Note:
Russian air-delivered cluster bombs, such as this one, are often named using a designation that is a compound of the names of the cargo (carrier) bomb and the submunition it carries. For example, this RBK-500 unguided, air-delivered cluster bomb carries 268 PTAB-1M HEAT submunitions, and is thus designated the 'RBK-500 PTAB-1M'. (ARES)