Calibre is one of countless names producing external backup battery packs, a name you probably have never heard of either. So what Calibre has done to make itself shine like a diamond in a the rough is create one of the more influential backup batteries that we have seen. With a first-class, ultra-clean design we swear could be based off of a leaked schematic of a soon-to-be-released Apple product, the Ultra'Go mini has already done its part in grabbing our full attention before knowing what it does and how well it does what it should do. Calibre's Ultra'Go mini is not much different from other batteries of its kind in that it'll charge just about every one of your USB-powered gizmos except that the Ultra'Go mini sells itself as the world's first ultra-compact battery pack to feature vibration signalling. A vibrating external backup battery? That's certainly an intriguing first for us. What does it all mean though? Let's get straight into the thick of it then!