Blackburn "race" water bottle cage.
Been using them since the 80's. Nicely made, simple, light and strong.
So good that they never had to do any changes to the design since the 80's and was copied by hundreds of other makers. You can buy a brand new one today and put it on a 30 year old C&V bike and it will look period correct.
I'll take it any day over those "Ciussi" cages with the fancy buttons on them....