Hi Mark, 
 
Thanks for your follow up question. 
 
A King Size Zip and Link mattress will give you 2 independent mattresses measuring 2ft 6" x 6ft 6" Similarly, a Super King Size mattress is 2 mattresses measuring 3ft x 6ft 6". 
 
People would opt for a Zip and Link mattress for many different reasons; The main reasons being ease of turning as you're not then struggling to turn one full sized mattress, where access to your property is restricted so you won't fit a one piece mattress in or where one user tends to disturb the other as you can't transfer movement between the springs. 
 
The Origins Pocket 1500 is a true medium feeling model in the top layers providing a slight sink in sensation but not too much. 
 
If you think access to your property might be restricted then you need a clearance of 5ft from the 5th step up your staircase to the top of any overhang or bulk head. 
 
I hope this has assisted further but if you do have any further queries please don't hesitate to contact us on 0161 437 4419.
 
Kind Regards, Lee.