• Built to Last: It is made of quality material, which is durable to use for a long time. providing good performance and durability
• Emission-line Filter: It is an extremely narrow emission-line filter that works by allowing a 5nm bandwidth of light, centered on the 656.3nm wavelength through, and blocking the transmission of contrast-killing light pollution wavelengths
• Reduces Natural Light Pollution: Wavelengths that are responsible for natural light pollution, or skyglow, are drastically reduced, as is artificial light pollution caused by high- and low-pressure sodium vapor and mercury vapor lights
• 300-1000nm Wavelength Range: This H-Alpha filter also blocks infrared wavelengths from 300nm to 1000nm so you don't need a separate IR-Cut filter (This H-alpha filter is NOT for use on the sun)

Specification:

• Size: 2-Inch
• Substrate Thickness: 1.85mm
• Clear Aperture: 44mm
• Wavelength Range: 300-1000nm
• CWL: 656.3nm 
• FWHM: 5nm 
• Blocking: ≥OD5
• Peak transmittance: ≥90%
• Surface Quality: 60/40 
• Surface parallelism: 1/4λ
• Thread: M48x0.75
• Single Thread: Yes
• Net Weight: 12.5g