Different Versions of HRM-Tri?

My original strap (that I got with my 920xt) had the blue grippy rubber (Just like the HRM-Swim) around the electrodes. From the image on Garmin's website, the HRM-Tri that comes with the FR945 has the same grippy rubber, but it's black instead of blue. After my dog chewed up my HRM-Tri, I bought a new one off Amazon. This new one has no grippy rubber around the electrode, instead it was the same type of smooth rubber as the electrode.

This new HRM-Tri functions the same as the old one and as far as I can tell it stays in place just as well too. My natural curiosity just made me wonder why the different designs.