For putting it on the actual nail it applies nicely and I do feel the difference in how healthy my nails and cuticles feel.
If you don’t have very long periods where you have bare nails, a small or medium size is plenty, not a whole lot of product is needed.
I suspect the tiny one is going to last quite some time and I’m very satisfied. If you mostly have your nails painted, solar oil might be worth buying a heck of a lot more of