Active Shutter 3D Glasses 4 Pack

One pair is $37, 2 pair are $35 each or for the best deal 4 pair for $27.50 each. Pair with a Panasonic 4K upscaling bluray player and 3D has never looked so crisp and sharp. The only con i see is they are a bit big for kids. They work well, pair easily, and for us are reasonably comfortable. We haven't tried to see how many movies we could get through without recharging, and just plug them in after every time we use them. We have 8 and just keep a 10 USB brick with the cables and a tray to keep them in by the entertainment center. If you leave the room they disconnect, and pair again. Our projector flashes a notice that they've repaired that could be bothersome, but it's not a hassle and is quick. The only complaint is that the included instructions are very brief. They do not tell you how long to charge

While the glasses did sync with our projector, they just didn't do that great of a job. Battery life seemed very good and they charged quickly. They're one-size fits all, and therefore aren't the most comfortable for long viewing times. In the end, these weren't for us and we returned them. If your system supports creating 3D out of 2D from 2D material, I would not recommended that approach -- doing that actually made most of us feel like we had a headache after 15 minutes of viewing it.