I never used a lot of the thumb grip accessories available for Leica cameras until I got my Leica Q. The Match Technical Thumbs Up grip for the Q has made all the difference in the world, and I can't imagine shooting without it now.
When I got my Leica Monochrom (Type 246), I wanted to get another Thumbs Up grip, but the problem was that I wouldn't be able to use the Thumbs Up and the Leica EVF-2 in the hot shoe at the same time. Since I use the EVF-2 whenever I shoot my favorite lens, the Leica f/0.95 Noctilux, it was a non-starter to consider the Match Technical Thumbs Up grip.
Thankfully there is no shortage of inventive people out there! An English gentleman has designed a different product for the Leica M bodies called the Thumbie that provides the same grip benefit, but without hogging the hot shoe. The Thumbie is also significantly cheaper than the Thumbs Up grip (around $30-40), but it isn't available at mass retailers like the competition. I found mine on eBay and it was delivered to my home in the UK two days later.
The Thumbie arrives in a silver box - although it's not a Leica silver box - but seriously, who is that snobby? Inside is the Thumbie grip, some spare adhesive strips, and instructions for installation. Nothing fancy.
Of note, the Thumbie fits a whole range of M bodies - the Monochrom uses the same version as the M240. Versions are also available for the M8, M9, film bodies, etc.
The instructions are fairly straightforward and suggest that the double sided tape (which is apparently designed for use in the automotive industry) will not damage the finish of the Leica body, assuming you remove it without a jackhammer.
Thankfully the adhesives for the Thumbie are pre-cut, which is good, because the actual flat surface isn't a simple rectangle. The little notch fits above the scroll wheel on the back, and the provided adhesives are cut pretty close to size. Good, I don't want more arts and crafts projects!
Before installing the Thumbie, I wiped the back of the Monochrom body down to ensure there was no oil or grease from my hands on the surface that could interfere with the adhesive. The instructions call for a very tiny amount of dish soap added to a bowl of water and to lightly coat the adhesive in this soap water mixture prior to adhering the Thumbie on the camera. This allows you to carefully setup the Thumbie in precisely the right location before the glue sticks. Clever.
The installation overall was very easy, and took less than 5 minutes (including time spent taking photos for this review). The instructions suggest waiting 30 minutes after installing to ensure the adhesive is fully stuck on - after 30 minutes the attachment felt pretty strong.
The Thumbie nests right next to the scroll wheel on the back of the M bodies, so I was a bit concerned that it would interfere with the operation of that dial. However, I was pleased to see that the Thumbie's smaller size and profile keeps it from interefering with the dial's operation.
In all fairness, the Thumbs Up grip certainly is beefier and feels more solid on the M than the Thumbie...but it is also three times the price, and hogs the hot shoe. I played with the Thumbie for awhile after installation and it did a satisfactory job of giving my right hand more tactile control and surface to hold the camera body. It may not be as sexy as a naked camera, but I'm a real photographer, who really uses their camera to take real photographs. And if an inexpensive attachment prevents some hand fatigue and makes it easier to carry my Monochrom with the Noctilux all day, then sign me up.
Time will tell on the durability of the Thumbie. Assuming that rubbing along my pants and side doesn't cause it to rub off into the street gutters one day, I think I'm a satisfied customer. And if that ever does happen, I'll update the post to let you know.
Overall, for the money, Thumbie may be one of the best purchases I've made for my Leica!