The Chroma LoGlow Light Pollution Filters - Blocks common spectral lines from lighting sources:

These filters provide balanced color for the visible spectrum while blocking most emission from metal-halide and vapor lamp sources which together contribute to sky glow.

Sizes to Choose from:

• 1.25-Inch diameter: Mounted in a threaded ring
• 2-Inch diameter: Mounted in an M48 threaded ring
• 31mm diameter: Unmounted, x 3mm thick
• 36mm diameter: Unmounded, x 3mm thick
• 50mm diameter: Unmounded
• 50mm x 50mm square: Unmounded, x 3mm thick
• 65mm x 65mm square: Unmounded, x 3mm thick

Typical spectral performance is ≥ 94-percent average across visible pass-bands; Blocking is ≥ OD1.4 at  metal-halide and vapor lamp lines

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This Filter Blocks Common Spectral Lines from Lighting Sources!