Definitive Technology DI6.5R Disappearing In-Ceiling Speaker Open Box (Each)Extraordinary High-Performance Speakers that Virtually Disappear in Your Room!Flangeless design & micro-perf grille minimize visibilitySimple to install no spackle work required8-5/16 (21.04 cm)total visible diameter is about the same size as competing 5-1/4 models.Perfect for use as side/rear surround speakers for Mythos and BiPolar-based home theater systemsLatest generation BDSS drivers for audiophile-grade sound qualityPivoting Pure Aluminum dome tweetersAxial