Pros: Does exactly what it's supposed to do. No silly handset lifters

Cons: All electronic hookswitches are rather absurdly priced for what's basically a few plugs, some very basic circuitry, and maybe a micro-relay or two.

Pros: Works flawlessly between the Digium D40 and the Plantronics CS55 headset.

Cons: Expensive

Overall Review: It astounds me how much money Plantronics gets away with charging for a micro-relay or two and a few plugs and wires. I doubt it costs more than $5 to make these things, but you gotta have 'em...

Pros: Top quality battery without the added cost of buying APC's "certified" batteries. Lasted 20 minutes powering a workstation and two monitors when I tested it, which was longer than advertised, and longer than APC's specifications for the ES550 it was installed in.

Cons: None

Overall Review: The APC re-branded RBC that I removed was actually a CSB-manufactured battery, so I'm quite confident that this will be a suitable replacement. Basically just cutting out the middle-man. I'll be ordering more of these as our other UPSs age out.