Philips Sonicare1100 Power Toothbrush, Rechargeable Electric Toothbrush, White Grey HX3641/02

This 1100 model has a single intensity. Is the intensity of the 1100 equivalent to the higher or lower intensity of the 2100?

I was sent model hx364w3 not ‎HX3641/02. mine is very weak. does it get as strong as older models after beginners mode?

Does this take the same head pieces as aquasonic black series ultra whitening toothbrush?

Do you not brush hard like a manual?