Is the Source™ Toothbrush head the same size as the Big Brush™/Flex™ Brush?

The Source™ Toothbrush has a 50% smaller head than the Big Brush™ and Flex Brush but it still has 200-300% more bristles than an ordinary toothbrush. All of our replacement heads are interchangeable, so you can use the Big Brush Replacement Heads with a Source and vice versa. We're overachievers like that.