I went through this exercise a couple of years ago and after a lot of research I purchased the Caterham specific Scroth harnesses which CC fit to their race cars.
I was advised by Dave Kimberly at Demon Tweeks and many helpful members on here, I am very pleased with them, they where big money but DaveK gave me a good deal and they have proved to be well worth the extra cash. Easy to adjust, soft webbing and removable buckles amongst other features and the Luke/Caterham 6 point crutch straps fit the Scroth buckle..
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TRY THIS