Lying on your back on the flat bench (straight/flat position), hold the weights in front of your chest with your arms bent and press the dumbbells against each other (elbows close to your body pointing downwards), grasp the dumbbells with a neutral grip so that your palms are facing the respective side, push the weights upwards to bring your almost fully extended arms into the holding position, then lower/bend your arms back to the starting position.
Attention:
Do not fully extend your arms in the holding position and do not place the weights completely on your chest when lowering. Press the dumbbells firmly against each other during the entire exercise sequence.
Lighten:
Less weight.
Harden:
More weight.
Variant I:
An incline bench or even a decline bench.
Variant II:
Hold the weights shoulder-width apart instead of pressing the dumbbells against each other.
Variant III:
Replace the dumbbells with a weight disc and pinch the disc between your palms (disc horizontal to the floor) or grasp the weight disc with both hands at the edge (disc horizontal to the floor) for less strain on the chest muscles.