I have a 160g caique. Guidelines show 100-299g for size small and lists birds like starlings which are smaller than caiques. All listed as "small" examples.
Size small collar itself is slightly over 30g.
It is MASSIVE and super heavy. Need a really good pair of sharp scissors to make it usable and safe for smaller birds.
I would not recommend this product for birds under 200g.
Great product my birds love to pick it out of there water
My bird ripped the the rubber cushing within 30 mins. So we had to toss it hes still plucking away at his feathers For the price it was i would say poorly design
Started giving the flock daily doses, a bit to early to see any effect, but know this is a good thing for them .