Every IXXI is suitable for hanging outdoors. The cards are made of high-quality synthetic matte material called Synaps. This material is waterproof, tear-resistant, and does not warp. Like any other photo product, sunlight can have an impact on the print over time. When you also attach the IXXI at the bottom, you don't have to worry about it blowing away.
For the proper attachment, you can choose the outdoor kit. This kit includes 5 screws and 5 plugs. You alternate between attaching a Powerstrip and a screw. In this video, you can see exactly how it works: