PRICE IS  for 1 STACK 

Stub stacks suitable for all 1 1/2  SU carbs fitted with pancake  airfilters

Please note the size  of 1 1/2 is the size of butterfly on a SU carb . 

SU carbs are tapered hence the choke is smaller on the filter side than the head side . 

Stacks are supplied slightly undersized so they can be ported to match exactly the choke size