Briz-M is a twin upper stage consisting of a core module (using Briz-KM as the baseline) and a jettisonable add-on toroidal tank surrounding the core. It is powered by a pump-fed gimballed main engine, the 14D30.
The Briz-M comprises a dual upper stage: a core module based on Briz-KM and a detachable toroidal tank encircling it. This system uses a pump-fed gimbaled main engine, the 14D30, to function.