NCE has upgraded their SmartBooster for the PowerCab system. It has been increased to 5 amps, allows six recalls per cab, and supports auto-reverse and circuit breakers. It also looks like the connectors have been changed in the photos. The new designation is SB3a. I am using the old SmartBooster which is rated at 3 amps. Not sure if the new one is necessary in Z unless you have a very large layout and are running lots of engines at the same time. NCE supposedly will take your SB3 in trade in on a new one and you only pay the difference between the two. Their DB3 booster has also been increased to 5 amps and is now the DB3a.
I looked at the photos on Tony's, and from what I can see, there is no point in buying a PB-105 5A booster when the DB3a 5A booster is compatible and does the same thing for $30 less?