60 Day 100% money back guarantee. This mounted excitation filter was removed from the optical wheel of a PerkinElmer Wallac ViewLux microplate imaging system. The mount is marked 525/20EX 4501 BARR#4. Its nominal specification is a 525 nm center wavelength with a 20 nm bandwidth, corresponding to an approximate 515-535 nm passband. This specification matches PerkinElmer ViewLux catalog reference 1430-5070. A localized edge or coating defect measuring approximately 9 x 3 mm is visible and shown in the close-up photograph. The effect of this defect on optical performance is unknown. The filter has not been tested or spectrally measured, and transmission, blocking, coating performance, and compliance with original specifications remain unverified. Minor dust and cosmetic mount wear may be present. Includes one mounted optical filter only. Keyword Block: perkinelmer viewlux, 525/20ex, excitation bandpass, barr associates, fluorescence optics, microplate imager, 1430-5070, laboratory optic