Product:Pro UD Carbon cage
Price as reviewed:£49.99
If keeping your water bottle in place is a key concern for you then this bottle cage from Pro will absolutely do the job, only the Elite version with a physical clamp is more secure.
For normal riding it’s overkill and will actually slow you down – the bottle is that tight in the cage that you have to pause pedalling to concentrate on inserting or extracting it.
Then there's the price: 50 quid is way over the top. It's good but to my mind it's not good value.