Etalons from Spectra Physics, Sale is for one.
One says "Vis"= visible" on it and an obvious typo, "EATLON". I don't know the wavelength range.
15mm dia.
These all have the same part # though some appear to have a silvery coating, a couple have a mauve coating.
Let me know if you prefer one over the other or I'll send you a random one.
I combine ship to keep costs down.