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 EW0800-K Replacement Brush Doltz Clean & Brush 2 Pieces Black Japan
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-W Replacement Brush Doltz Extra-Fine Hair Brush Large White F/S
