Description
-No serial #
-Chrome finish
-Special prototype 35mm F3.5 UNIQUE Summaron lens
-Made in the early 1950's in Wetzlar, Germany for the pre production Prototype M NULL cameras
-Black meter focusing scale version with infinity focusing lock

These were NON SERIAL # lenses that were made for test or experimental production along with either the NULL SERIES M camera ( First prototype M3 cameras ) or with special featured cameras such as the BETRIEBSK for factory use only. 
There were never made to be sold and true UNIQUE Prototype when they were working the make the regular production.

This one is a UNIQUE PROTOTYPE that has a characteristic unlike any other. You can see in the last photo how they differ. 
The one of the very left is the earliest regular production SM LTM 35mm f3.5 Summaron with the small serial no. ring holding the front element ( this is how the lens came apart )
The middle photo is THIS PROTOTYPE version, STILL WITH THE SMALL RING that hold the front element, BUT ALSO with the LATER STYLE deep barrel multi ring solid black ring.
The last photo on the very right is the regular production 35mm f3.5 M and you can see non had the small ring holding the front element. It just has the long multi ring barrel as one piece. 

This truly is a UNIQUE prototype as a transition from when Leica was going into the M series lenses. Larger barrel design.
This has NO SERIAL #, UNIQUE PHYSICAL DESIGN and also has the proper FACTORY PROTOTYPE DESIGNATED rear clear M cap. 

Similar lenses are the 35mm f2.8 PROTOTYPE in this same barrel design which last sold on Oct 9 of this year at the WETZLAR AUCTION LOT 93 with the same transitional front ring for 26620 EURO ( Appox $29500 USD$ )

Details
-6 elements 4 groups
-Aperture range: f3.5 - f22
-64° angle of view
-E39 filter mount
-Cat No. 11105 (SOONC-M)

Includes
-Front metal lens cap
-Special PROTOTYPE M clear plastic rear lens caps

Cosmetics 9/10
-No dings, dents or major marks
-Really in very nice collectors condition
-The black front PROTOTYPE transitional ring is very clean. 
-Body is very nice!

Mechanics 9/10
-Focusing is smooth
-Aperture clicks are crisp

Optics 8+/10
-No fungus, separation or scratches
-Very VERY Minor haze which is common on these lens and can be cleaned. * I don't want to open this prototype lens but can be easily clean if the new owner decided and I can provide that service if requested *

This came from a Leica factory associate and tremendous find. Really something special and a must for any serious collector or enthusiast! Truly a UNIQUE PROTOTYPE and a one time opportunity to own a piece of Leica history!