Easy to get the old ones off (just pull a bit and then a bit more at another bit), the put the new ones on. Most of the time they will not fall out. I bought some cheap bikes for me and partner as a pandemic activity. I had to put a pen under my phone to lift it high enough to make contact and get a charge . It looks like a big phone built into the dash! Peel the cover, get the adhesive hot enough to just start bubbling, and youre good to go. Have used it with elastic bands and did some callisthenics on the bench for about a week now. Keep away from dogs who love fluffy things :) The build quality is excellent and the gauge is accurate. While trying to find a solution, I heard about this product.