The Tris Amminium family differs from the Tetrakis in that its dyes have a narrower absorption at their peak wavelengths ranging from 900 to 995nm. 

The tris dyes are organic salts available in monovalent and divalent forms.  The monovalent salts are more thermally stable, absorb at a higher wavelength than the divalent salts, and are more soluble in organic solvents.

Organic solvent soluble dyes
Epolight™	lambda max, nm	charge
2063	906	divalent
2062	977	monovalent
2066	978	monovalent
2057	990	monovalent
2164	993	monovalent