LightSpan® LS2-3354 is from LEDs to fiber optics, NuSil Technology's LightSpan™ brand product line delivers the most comprehensive line of refractive index matching adhesives, encapsulants and thermosets available.The benefits of silicone include the following: Thermal Stability Low Ionic Species Maintain Optical Clarity (90% minimum @ 400nm) Low Moisture Absorption (<0.4%) Optimization for UV Resistance Adjustable Cure Low Outgassing Low Shrinkage, <1% Low Modulus: Stress reduction for bonding materiaLS with different coefficients of thermal expansion Gernal Purpose: Optical GeLSComments: Contains adhesion promoter, use with Phosphor.