Manual seat pedestal tube, has a tapered base, which slides through the base to the top of the taper to give the lowest height range of range 405mm up to 690mm. The tube goes through the floor 100mm.
You will need to add top part number 63760 and base part number 64070 to complete the set. These can be purchase from Norlfolk Marine.
The prices are top 63760 £102.11 and base 64070 is £55.20
I can ship to the US please email, don’t use the contact form as it’s not working.