Yamaha's MSP3A is a powered monitor with a unique twisted bass port
Yamaha NS-SW200 front firing subwoofer with patented twisted flare port bass 220 VOLTS NOT
MSP3A 4" 2-Way Powered Monitor with Twisted Flare Port | Yamaha | Leisuretec
New *Dimple" Precision Ports... - Techtalk Speaker Building, Audio, Video Discussion Forum
Yamaha NS-SW100BL Twisted Flare Port Subwoofer
Twisted Flare Port - YouTube
Yamaha's NS-SW300
Yamaha's NS-SW300
Yamaha's NS-SW300
Yamaha's NS-SW300
Yamaha Subwoofer Speaker with 130W Output Power Twisted Flare Port (Black) | eBay
Yamaha HiFi NSSW050 B 8" Active Subwoofer w/ Twisted Flare Port & Advanced YST II - Black - Canada's Favourite Music Store - Acclaim Sound and Lighting
Yamaha Launches MSP3A Compact Powered Monitors With Twisted Flare Port | audioXpress