I bought a 5 1/4" infinity reference component system for the front and two way 5 1/4" for the rear. I read a post on the speaker sizes on this site that said 5 1/4" but they are indeed 6.5". The crossover unit that comes with component systems separates the high frequencies to the tweeters and mids to the 5 1/4". The rear two ways are highs and mids. Despite the smaller speakers the volume was able to get louder without distortion.