I purchased 2 this afternoon, and they seem to work fine with my cobra 220's. My cobra 310's, however, will not "ring"(call) the uniden or the cobra 220's, but the 220's and the uniden will call the 310's. After e-mailing Cobra twice about this, it was finally explained to me. The vibra-alert feature of the 310's require a digital signal, so that is what the 310's communicate with. The lower-end Cobra's and most other 2-mile range FRS radios use an analog signal, so different brands are compatible as long as the signal is the same. I was finally forced to admit to my DH today that I just wanted to like the 310's so much because I had so much invested in them(the re-chargeable battery packs with chargers @ $140 + radios themselves at $80 each). I personally like the water-resistant feature, vibrating alert, and cute little fold-down antenna of the 310's, but the 220's are just as good, even with the non-folding antenna and no vibrating alert. After purchasing 2 of the Unidens today, and playing with them for a few minutes, I decided I liked them better than the 220's! I went back to the store(30 minutes away), and purchased 2 more at 8 pm! The Unidens are smaller than most other radios, with an "integrated" antenna, and a really cool design(according to my 9-year-old). These radios have 5 different "rings" like a cell-phone, and a vibrating alert, which I have to agree with Granny that is rather weak, but at $10 each, a vibrating alert at all is a plus. The only thing that the Unidens do not have that might be useful at WDW is the water resistant feature, but again, at $10 each, I can't complain. I looked at this exact model(420) at Wal-mart a week ago, and it was clearanced at $30 each. The local Wal-mart also carried a lower model(I think 240?) clearanced at $15 each, and some Motorolas clearanced at $22 each(I think the new GMRS radios are driving the price of the FRS radios way down). For anyone who missed the $10 sale, check your Wal-mart. I looked at both Wal-mart and Circuit City for the rechargeable battery kits for the Unidens without any luck. Each radio requires 3 AA batteries, which should render 50 hours of service(according to info included with radios), so most people would probably use 1 set of batteries per trip. I decided to purchase 24 AA batteries(2 sets for each radio) for now, and if they work well at WDW I will purchase the rechargeable kit later. Thanks Cindala for the heads-up!