What makes the SHOOC a joy to use is the fairly 1:1 (1x) view it affords in framing, allowing you to essentially shoot with both eyes open - making for easily used framelines. Some come with a little leather snap case, others with the original box. Currently, they go for $85-150 (or more) depending on condition - though you shouldn't pay more than $150 for a mint copy. The biggest problem seems to be the usual nicks and scrapes and hazing of the optical elements. They do exist though, as the photo above illustrates. Let's face it, 135mm was just not a hugely popular focal length for the M system (though perhaps undeservedly so). The SHOOC finder was produced from 1951 through the 1970s, but is still relatively easy to find on the used market. If you don't have the framelines, then a finder is a necessity if you're not the type to zen your shots. Even the strongest magnifier currently available, the Leica 1.4x won't improve the view drastically, though it will definitely help with focusing and accuracy. While some film bodies and the M9 have 135mm framelines, you'll be framing with the smallest set available - even on models equipped with a. Unfortunately, for M8 shooters, you'll need a finder with 180mm framelines (of which there are some, but few - and somewhat hard to find).
The Leica 135mm finder, also known by the name "SHOOC" - makes a great companion to the 4/135 Tele-Elmar-M or other 135mm lens on film or M9 bodies.