Extension Ring for Kochmann Reflex-Korelle Lenses

An extension ring that fits Kochman Reflex-Korelle (and other compatible) which unscrews to split - perhaps there's a tube that can be added to increase length.  I believe it is necessary for using certain lenses with the Reflex-Korelle to give sufficinet clearance for the mirror to lift.  In very good used condition.

P&P in the UK will cost £1.50; Airmail will cost £2.50 in Europe or £3.50 for the rest of the world.  Collection from Farnham, Surrey is of course free and very welcome.  All standard forms of payment gratefully accepted - but non-UK bidders please note I can't accept cheques or bank transfers in any currency except Sterling unless the buyer is prepared to pay the (embarassingly high) bank charges that I will be charged and wait until the payment has fully cleared before I ship.