Thanks, but perhaps I wasn't specific enough. I think you have measured the length of post below the collar.
I don't have much seat post extending out of my frame, so what I need is the distance from the rail of the saddle to the bottom of the red collar. I will have to run the post fully inserted in the frame and need to know if the extended position of the post will be too high for me or not. I guess the measurement is approx 150 mm (20mm collar, 100mm of extendable post and 30 mm for the clamp) but I'd like to know it exactly before placing my order.
Would you be able to measure this?