The air tag holder has a plastic carabiner and is compatible with a key ring or backpack. Tested in ABS, works properly. Every printer has a different tolerance, try it before and, if needed, scale it a bit. 
0.2 layer, support not needed. If you have any questions or doubts, please get in touch with me! Please leave 5 stars if you like it and post a picture of your print.

Please check my other models:

https://www.printables.com/model/1149589-air-tag-secure-holder

https://www.printables.com/model/67223-air-tag-secure-holder

https://www.printables.com/model/802742-new-square-air-tag-secure-holder