I have the Poker Genie and I would not leave home with out it.  It is a small timer that has easy to use functions that displays blinds and signals to let players know the blinds have gone up.  The best part is that it has a plug for power and no batteries to be changed.  For some reason the Poker Genie has stopped selling their great product and I found out in March that they are going have them available for June 1st.   I will probably have them on sale for $49.99.