Received what I ordered very quick! I was pleasantly surprised that the items were just as described.

The brush head has a good firmness, not too hard, not too soft. I should mention that I was sent a free sample to use for this review.

I received a free sample of this product to review and was quite pleasantly surprised. I`ve had other brushes in the past that have not held up as well. This one seems to be a good mix of firm, yet soft, and not getting all bowed out right away. It`s small enough to get around some of my crooked teeth. I recommend this.

The 4100 Sonicare Brushhead works amazing with toothbrush. The bristles are just perfect to get between those hard to reach areas. I love how thick they are too - they stay that way for a long time too. I have been using this for almost a month and I have to say the bristles are just like day one of using. They haven`t flatten out or anything. I am impressed on how well its holding up! Easy to install on toothbrush too! Win WIN!

Full Disclosure: I received this product in exchange for my unbiased opinion. ITEM: Philips 4100 Sonicare Brushhead FEATURES: Pressure sensor feature (toothbrush makes a pulsing sound as a reminder to ease off on the pressure) is a nice touch, especially for children or even for adults with sensitive teeth and/or gums. It claims to remove 7 times more plaque than a manual toothbrush. While I obviously can`t confirm the accuracy of that statement, I will admit that my teeth do feel noticeably cleaner after using a Sonicare than when using a manual toothbrush. CONVENIENCE: The `BrushSync` technology alerts you (via a light on the handle and a short beep) that it`s time to replace your brush heads, so no more guessing when it`s time to replace them or, worse, using a brush head that is well past its prime. PROBLEMS: One minor complaint would be that this doesn`t come with a brush head sanitizer like some of the other Sonicare models do. But, this is one of their lower-priced models, so that`s understandable, I suppose.

STORAGE I received this product in exchange for my unbiased opinion. Brush head was easy to install on the brush. ASSEMBLY EASE of Use The toothbrush head was easy to install and place on top of the toothbrush. PRODUCT FEATURES Overall the brush head functioned very well and I would recommend purchasing it to get a great clean. In addition I enjoyed the reminders and hints to practice better oral hygiene provided by the brush head. Specifically these hints included the Pressure sensor. Toothbrush pulsed when I needed to reduce brushing pressure. STABILITY The brush head seems to be very stable. I have no worries and believe that this brush head can be used long term. PROBLEMS I experienced no problems with the toothbrush head.