Product review (3 stars): Necessary but not Sufficient
The concept for this freezer meter is simple and elegant.  If your freezer gets above 32F (0C) for too long, the water melts and the ball moves down, providing a warning even if the temperature goes back down before you check this.  Unfortunately, it operates at 32F, not 0-10F as a freezer should.  So, yes, it will warn you if your food completely thawed, but it won't warn of inappropriately high temps that stay below freezing.  You'll still want a freezer thermometer that you check from time to time.  It attaches with a Velcro cable tie, which should work fine in most freezers.  Our side-by-side has no rails or wires to which to attach it - check your freezer before ordering.  At the current price, this is affordable insurance against inadvertently eating refrozen food.

Overall, this is an effective indicator of extreme temperature problems in your freezer, but you'll still need another method to confirm proper operating temperature.

Review of:&nbsp;<a data-hook="product-link-linked" class="a-link-normal" href="/Freezer-Meter-Frozen-Food-Safety-in-Seconds/dp/B00OR2M7GC/ref=cm_cr_arp_d_rvw_txt?ie=UTF8">Freezer Meter Frozen Food Safety in Seconds</a>