Looking for motorcycle mobile phone holder Nokia CR123 received good points. It is elegant and bulletproof, as Nokia mechanics has always been. Unfortunately it has long legged suction cup mount, not suitable for motorcycle. Connection ball to mount is 15mm, same as in Marinetech catalog product (M6x15 Massive Ball with internal thread, stainless steel AISI304). And it fits exactly!

Now my combined mobile holder is small and elegant!