The head is 3.2mm and the neck is 4.2mm, so it can reach the back teeth.
Panasonic EW0801-K Replacement Brush Doltz ultra Fine Hair Large
Panasonic Replacement Brush Doltz Clean & White Brush Set of 2 Black EW0820-K
Panasonic EW 0984-W Replacement Brush Doltz Clean & White Brush 2-Piece Black
Panasonic EW 0961-W Replacement Brush Doltz Clean & White Brush 2-Piece Black
Panasonic EW0801-K Replacement Brush Doltz Extra-Fine Hair Brush Large Black F/S
Panasonic Replacement Brush Doltz Multi-fit Type for Ion 2 Pieces White
