As you can see there are 2 different kinds of Helter Skelter, the more modern square style, and the traditional older Pepper Pot  /lighthouse style.
 
The view from the top over the whole event is breathtaking just before you whiz round and round to the bottom, a traditional ride enjoyed by all age groups.
 
They measure:   Square style is 38ft high and 30 ft square at the base and the Pepper Pot style is 50ft high and 35ft diameter at the base.  
 
The biggest difference is in the cost as there are very few traditional Pepper Pot ones around now and they take a long time to erect which makes them rare and expensive, whereas the square ones are more easily available.    
Before you close this page check out the astroglide, its the same as you sit on a mat but rather than slide round you slide straight but go over some humps, its as much fun but  about £300 - £400 cheaper.