More accurately, this is the SRB (Schneider-Renault type B), a precursor prototype to the B1.
It was used to test a 47mm AT gun in place of the casemated 75mm (tank SRA).
The B1 was in fact a composite tank, made out of the best parts from prototypes from constructors Renault, FAMH and FCM.
Included : a side view of the same, with an added infantry-carrying test trailer (which, surprisingly, got rejected ::)).