A multiparticle detector based on two large (6 m long) streamer chambers triggered by surrounding scintillation hodoscopes and viewed by cameras via image intensifiers is being assembled at CERN and tested at the ISR. Its purpose is to perform a first rapid visual survey of the new energy region afforded by the SPS pbar p collider. Charged tracks can be observed down to 3/4°, and hence over most of the pseudorapidity range (|η| lesssim 5.0) covered by high multiplicity events. Lead glass plates are being placed within each chamber to convert gammas produced within the same η range. The apparatus is hence particularly appropriate for the detection with high efficiency of the so-called Centauro events, thought to be characterized by very large multiplicities (langlenchrangle ~ 100) and by very few accompanying neutral particles.