Growl’s interactive bag lets you punch your boxing trainer in the face

The Growl trainer has a screen you can punch without regretting it later. | Image: Growl Growl is a startup launching a wall-mounted fitness device that uses a combination of projectors and sensors to give you a life-size boxing coach to train with. Unlike similar interactive trainers such as the Lululemon Mirror or Tonal, the Growl encourages physical interactivity with its screen that doubles as a punching bag you can actually hit. However, just like those smart home workout machines, it&rsquo