Instruct: Classify Amazon reviews into positive or negative sentiment
Query: poor charging design. so pretty but i have gotten tired of just looking at it

Quite impressed with other plantronics bluetooth devices. Own a 510 and it works seamlessly with my macbook, blackberry and the bluetooth base i bought it with. The 645, is a nice looking device, but either i have a defective unit, or the design is flawed. the headset slides into a sleeve, that has the the connections in the base to charge the headset, but doesn't seem to hold the headset in the sleeve well enough to keep the charge going. My unit won't charge unless i physically hold it pressed into the base unit. It doesn't appear to be missing anything, and it charges when i hold the two pieces together, so i call this a bad mechanical design and would recommend not buying this product, but the 510 or anything else instead.