look ideal, anyone using one in a standard cage?
This does, and works well one handed and seals perfectly:
https://www.camelbak.co.uk/bottles-c2/drinkware-c74/forge-flow-vacuum-insulated-stainless-steel-travel-mug-350ml-p441/s1291?utm_source=google&utm_medium=cpc&utm_term=camelbak-forge-flow-vacuum-insulated-stainless-steel-travel-mug-350ml-colour-dune-size-350ml-cb2477201035&utm_campaign=product%2Blisting%2Bads&cid=GBP&glCurrency=GBP&glCountry=GB&gclid=Cj0KCQiApb2bBhDYARIsAChHC9t7SpOupT3lvtvmhKBFiO0xAA7gVbqkE6zns8UOGduCAVW3a5OCdHAaApqOEALw_wcB
I use a LifeVenture flask most days in either a plastic SKS Topcage or a basic coated alu bottle cage. Fits well and is secure. Slight rattle over the bumps with the alu cage.
I use one of these. Fits perfectly. It's a bit scratched up now though.
https://www.tesco.com/groceries/en-GB/products/309347946