The 74061 MS260i Triple Holographic Grating Assembly is mounted in an individual, prealigned mount. Simply drop it in place, and program the grating specifications into the MS260i through the Control/Utility Program or Hand Controller. This grating assembly has a 1800 l/mm line density and has a peak efficiency of 65% at the 500 nm Blaze Wavelength. It's efficiency exceeds 20% over the 300 to 925 nm primary wavelength region. 925 nm is the MS260i's upper wavelength mechanical limit for this grating assembly. You can add and change gratings in the field without changing the instrument’s grating turret. However, you may have to replace your current grating assemblies. If you wish to convert your MS260i from this triple grating to a dual grating (to improve resolution), you will need to purchase the equivalent 74161 Dual Grating Assembly.