IDAS NBZ Nebula Booster Filter, 52mm, mounted dual bandpass, H-α and OIII52mm filter does NOT fit 2" filter wheels with 48mm filter threads! This is a larger filter with 52mm threads. The 48mm filter will fit 48mm aka 2" filter threads. 10nm bandpass for Ha and OIII respectively. IDAS proprietary flat top, steep cut off and off center design eliminates the emissions signal loss due to the spectrum shift until F2 speed. Available 48mm and 52mm mounted (2. 5mm thickness) No IR blocker required IDAS NBZ Filters are designed