For this reason, it is a good practice to follow the advice of the speaker manufacturer or an experienced enclosure designer when it comes to designing a ported system. It is very easy to screw up a ported box if you just guess at the size and length of the port or the tuning frequency for the box. For example, consider a speaker where the vent (port) is tuned to 40Hz (a typical tuning frequency). In order for a horn to be effective at 40Hz it would have to have a mouth area bigger than most speakers ( at the very least, several feet by several feet). SPKR PORT FLARED ID58XL120MM. Flared Speaker Box Port - 58mm dia x 120mm Long CAT.NO: CX2688 Unfortunately, this speaker is no longer available on Klipsch.com. Check out the R-10SWi Subwoofer with Wireless Capabilities or visit one of our Authorized Retailers. The Reference R-10SW subwoofer is the ideal companion whether you're looking to achieve a 5.1 system or a 5.1 on the Richter scale.