We are using two kinds of colour rings in Polish Black-headed Project: made in Canada and made in Poland. Some of the ringers have problem with putting a colour ring on the leg without break it. Rings crack especially when the temperature outside is below 0 degree. Then the material is hard and unextensible so using pliers is not good solution.
On the movie below i show the easy and safety way to colour-ring the Black-headed gull (Larus ridibundus). I used a colour ring prodeced by Interrex as example. It takes only few minutes. What you need is just the pen (should be quite thick to put the leg into) and glue. If you ring gulls in this way for sure you will never break any colour ring.