In addition to housing 11 sensors, the Nordco XL9-11 is a 9” (23cm) diameter RSU.
That means the Sperry 6” (15cm) RSU must rotate 50% faster and 50% more times in
order to achieve the same speed and distance as the Nordco XL9-11. This translates
into higher internal operating temperatures and more frequent maintenance and
replacement of the Sperry RSU components.