JBL Flip 5 PartyBoost Button Explained - Tom's Tek Stop
Amazon.com: JBL Flip 6 - Portable Bluetooth Speaker, powerful sound and deep bass, IPX7 waterproof, 12 hours of playtime, JBL PartyBoost for multiple speaker pairing, for home, outdoor and travel (Grey) : Electronics
JBL's PartyBoost is why I'll never buy another Bluetooth speaker - Android Authority
JBL Flip 5 Wireless Portable Bluetooth Speaker,PartyBoost,Without Mic) USB 20W | eBay