QSI uses the following model nomenclature: (s) indicates a mechanical shutter, (w) indicates a five-position integrated filter wheel, (-8) indicates that the integrated filter wheel has eight positions, and (g) indicates an integrated off-axis guider. A few models have a color option indicated by (c). Usually, the basic camera model without any of these features is indicated by (i). A good review article is [url=https://astronomy.com/~/media/Files/PDF/Equipment%20reviews/2011/0711%20QSI%20583%20CCD.pdf]here[/url].