In an effort to keep control of the raging Hulk inside him, Bruce Banner (Edward Norton) used a heart rate monitor to stay aware of his body and prevent his metamorphosis into the jade giant. Production noted this as one of the monitors used by actor Edward Norton while shooting the Brazil scenes.

This is the actual POLAR brand heart monitor watch screenmatched in all the close-up scenes of Brazil, thanks to the unique weathering pattern and two small scraps near the SUN day. Made from a black and grey rubber band with metal clasp item features a square face with the time and day. Item measures 10" long.

We can match this watch first with Bruce and his breathing trainer, reaching 146bpm; then on the night chase with Emil (Tim Roth), reaching 175bpm; and then seconds before becoming The Hulk inside the factory, reaching 199bpm. Currently not in working condition but presumably just missing fresh batteries.

Definetly, the key prop of the first part of the movie.

COA: Marvel Studios.