<div id="video-block-R2I7QIS5BSVGET" class="a-section a-spacing-small a-spacing-top-mini video-block"></div><input type="hidden" name="" value="https://images-na.ssl-images-amazon.com/images/I/A10hB9UoAZS.mp4" class="video-url"><input type="hidden" name="" value="https://images-na.ssl-images-amazon.com/images/I/71IFyMOuiOS.png" class="video-slate-img-url">&nbsp;Final UPDATE (January 15/2012): oK, 3,5 months of use and now this sneaker balls are almost finished (90% ) and still have some scent and them really seem to work controlling bad odor. This balls have been working under hard condition, always left inside my tennis shoes inside my SUV in hot weather.

I bought this shoe freshner in october 2011 for my tennis shoes. I play 2-3 hours x 3-4 times a week in hot weather .... oK, just imagine how sneakers get after ......

In the video you can see the plastic packaging and also get an idea of the size and the open/close mechanism that regulates the scent of the sneaker balls.

Inside the sneaker ball is a white small round shaped chemical substance that produces the scent.

The scent is really intense when new and with the holes fully open. It can be an annoying smell; it is kind of spicy, throbbing. I will advice you to regulate it closing a little bit the holes mechanism and don't let kids play with it, because it can precipitate sneezing &/or rhinitis.

Pro:
Size & Shape: Absolutely appropriate to fit sneakers.
Appearance: Smiley face... funny.
Effectiveness: I wrote a mail to sneaker balls costumer help (through their website) asking for the chemical substance inside the balls and the answer arrived promptly with the MSDS (material safe data sheet) PDF attachment. The physical data of the substance analyzed corresponds to a "yellow to yellow green liquid"; it also states that: "The specific components of this product constitute a trade secret....". The analysis says that it has "benzyl acetate", a compound amply used in scents, so it works as described.

But, I guess this product has some kind of naphthalene (alcanfor) substance. If this is right (would explain odor) besides freshener it would be bactericidal.

Con
Price: I hope the freshner to last at least 3 months (I will update this later: done). If it last longer price could be oK, but if the scent disappears before it will be expensive. Update: Yes, it last longer than 3 months under heavy working condition.
Package does not explains the scent so I do not really know how it works (minus 1 star).
Package suggested price is $4,99 ..... much less than price I paid here.

Overall Rating: 3,5 stars
Final Update (january 2012): Overall rating up to 4,5 stars.

Update (nov. 29): 2 months and still working very good!!!!. Yes, I think it have some bactericidal feature because it controls tennis odor great. The small ball shape is SUPERB for tennis shoes: 4 stars.
I have been using this with&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/YONEX-Power-Cushion-307-Clay-Court-Yellow-Black-Tennis-Shoes/dp/B0057HZP60/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">YONEX Power Cushion 307 Clay Court Yellow Black Tennis Shoes</a>.

P.S: I am an intermediate-advanced tennis player (NTRP: 4,5 level*);  I like technical aspects about racquets, strings, tennis shoes and tennis accessories. Nowadays I am playing 80% of my time on clay surface and 20% on hard courts. I play about 8 - 10 hours per week.

I have other tennis items reviews, maybe can be useful 4 u.

*If you want to know your tennis level visit: National Tennis Rating Program at the USTA web site.