Useless thumb switch. - MFT React Torch Mount and Vertical Grip

As a grip it's fine. For its intended purpose to activate a flashlight, hmm, not so much.

Difficult and finicky to adjust is an understatement. As someone else mentioned the thumb switch doesn't have enough travel to function reliably. Tried it with three different Fenix models.

Since forward travel is limited to 1/16" the tail button of the flashlight has to be right on the actuator to cycle it off and on. When the "safety" lock is on, so you don't unintentionally turn on the flashlight, the actuator still moves 1/32" or half its travel. Not enough to cycle the switch on and off but plenty enough to momentarily turn on the flashlight. Move the flashlight out enough to avoid unintentionally turning it on and the tail button is now so close to end of the pitiful 1/16" range of motion it can't fully engage the tail switch enough to cycle it on and off.

The lock mechanism is stiff and arguably difficult to actuate. Not too difficult with with a thumb maybe, not so sure about the forefinger of your weak hand.

I have a remote switch for one of the flashlights, unfortunately the pressure pad well is too narrow.

A major disappointment. Although it might be a great cigar holder if you smoke 'em while you're shooting. ;-)