Passive radiators with floppy suspensions are best.
Passive Radiators (Other Models)
Coutlet Premium Stereo Bluetooth 4.0 Aluminum Portable Wireless Speaker With Passive Radiator for iPhone and Android
2PCS Black Passive Radiator Loudspeaker Auxiliary Bass Speaker
TaoTronics Stereo Dynamic, crystal, clear andexceptional sound quality is provided by 2x 10w speakers and 2x passive radiators.
Passive Radiator calculator
Speaker Sale,Passive Radiator,Loudspeaker,Radiators,Speakers,Bass,Electronics
Description Size-defying sound with 10 Watts of digital amplification, Single speaker w/dual passive radiators for big sound, Speaker Add function (Stereo or Double Modes), Bluetooth audio streaming w
Bluetooth(R) streaming up to Rechargeable Li-Ion battery Up to 6 hours of play time 2 active drivers & 2 passive radiators for enhanced bass Speakerphone Multilanguage voice prompts Pocket sized Pink