There are two versions to choose from: The LEICA M6 TTL with its 0.72x viewfinder magnification and an additional model with a 0.85x-viewfinder. With its 20% larger viewfinder image - including the metering area as well as the bright-line frames - this second model is ideal for those photographers mostly using focal lengths as of 35 mm.
Further comprehensive information can be found in the respective chapter of the general catalog "Leica.The Program" and the Product Information, both of which are accessible as PDFs. The software neccessary to read the documents, "Acrobat Reader", is available free of charge from Adobe. Simply click on the respective logo.