SVBONY Dual Narrowband H-Alpha/O-III 7nm narrowband filters are specially designed for astrophotography in light-polluted environments and allow imaging under bright artificial light pollution and moonlight conditions to capture color images without using multiple filter combinations. Images are most useful with disposable color cameras; Can be used for imaging emission nebulae, planetary nebulae and supernova remnants; High transmittance and sharp cutoff can greatly improve contrast and show the most detailed information about deep sky objects; designed to cut off sodium drastically. Artificial light disturbances caused by steam or mercury vapour street lights and other unwanted interference (e.g. Sky Glow); Dual band narrowband filters are not suitable for visual observation and are not designed for imaging or observing the sun. Please note that the SV220 is not well suited for fast telescopes. Some users have reported that dual-band OSC filters paired with RASA can cause band shifts, thereby trimming HA data. Specifications: Brand: SVBONY Model: SV220 Name: Duo Band OSC Filter Size: 1.25" Substrate Thickness: 1.85mm Clear Aperture: 26mm Wavelength Range: 300-1100nm FWHM: OIII (7nm) & HA (7nm) 9. Blocking: > OD5; Peak transmittance: 500.7 nm@T>90%; 656.3nm@T>94%; Surface quality: 60/40; Surface parallelity: 1/4λ; Thread: M28.5 x 0.6; Single thread: yes; Net weight: 7g; Box contents: 1XSVBONY 1.25" 7 nm DuoBand OS C filter; 1 x PP material plastic box