Flex Belt Vs. Slendertone

Liz McClarnon - Photocall

Both the Flex Belt and the Slendertone Flex Pro Abdominal Muscle Toner are wide belts you wear directly on your skin to firm and tighten your abdominal muscles. Whether they live up to their claims is a matter of opinion. Slendertone Flex products also have two complaints on file with the U.S. Food and Drug Administration.


The same principle applies to both products, with gel pads inside the belt sending out impulses to area nerves. The nerves, in turn, send impulses to area muscles, making them contract and relax. These contractions mimic abdominal crunches. Each belt eventually needs the gel packs replaced.

Manufacturer and Price

Bio-Medical Research, LTD, located in Galway, Ireland manufactures both the Flex Belt and Slendertone products, with the Flex Belt as an advanced version of Slendertone’s Pro Abdominal Muscle Toner. The February 2014 price for the Flex Belt is around $200 and the Slendertone belt can sell as low as $60.


Flex Belt’s advancements include several enhancements over the Slendertone belt. The Flex Belt comes with an external rechargeable battery pack, whereas the Slendertone’s pack is built into the belt and is not rechargeable. The Flex Belt also includes an extension for larger waists, while the Slendertone comes in one size only. The FDA cleared both products as class II medical devices.

Class II Medical Devices

If a medical device is put into the class II category by the FDA, this means that it requires special controls above and beyond the general guidelines to ensure it is safe. Special controls include ongoing surveillance, meeting performance standards in the United States and international and special labeling.


Slendertone Flex products have two complaints on file at the FDA website. One complaint, filed in October 2008, reports the batteries exploded in the belt after only three uses, resulting in burns. The other complaint, filed in July 2005, says a Slendertone Flex product possibly caused a malfunction in the user’s cardiac defibrillator, sending a jolt that knocked him to the ground and resulting in a four-day hospital stay.