We offer integrating spheres for both Irradiance and Reflection measurements. The integrating spheres (SKU ending in "I") refers to spheres used only for irradiance where the total power of a source is measured (e.g., LED or laser). The irradiance spheres only have one fiber optic port on the side that goes directly to the laser. Reflection integrating spheres (SKU ending in "r") have two fiber optic ports one for the light source (top) and the spectrometer (side). The ISP series can also be mounted on the RTL STAGE sample holder for precise placement on/near the sample.