The cab I bought is 18 x 18 x 12 here is a link http://www.ebay.com/itm/351570326278 extra 12.50 for removable back and 18 bucks for the grill. We will see how it works out , I have a 1x15 Ampeg Bass cab that is much larger to try the guitar speaker in if I don't like this one. here are the specs for the rocketcab C-4 Custom 1x15 Extension Cabinet
Cabinet size: 22" W x 18" H x 11" D
Cabinet size: 22" W x 18" H x 11" D
Do as thou wilt . Aleister Crowley