This Bluetooth speaker from Ultimate Ears has several useful features. This model uses Bluetooth to ensure a fast pairing.
From Amazon
Ultimate Ears Wonderbooms 2 Wireless Speaker, Deep Bass, 360 ° Surround Sound, Waterproof, 2 Speaker Connection for Powerful Sound, 13h Battery - Concrete
Compadvance
ULTIMATE EARS Wonderboom 2
OnBuy
Ultimate Ears WONDERBOOM 2 Portable Bluetooth Speaker (Deep Space)