Ditto on the flip up lense covers.They are availablevirtually at every store that sells guns/ammo/accessories including gun shops, on-line and big box stores. I think mine are Butler Creek? There is often a guide for the proper size for various scopes (like the guide you use to find the right windshield wipers at the autoparts store). Even so, it's best to know the diameter of your objective and eyepiece or bring the scope in and fit it. Also,for many sizes, there are availble see-through flip up covers so you can actually look through the cover as it is protecting the lense. Likeusing a clear filter on your cameral lense to protect it.

They help to keep the lenses clean so you are less likely to have dirt and dust on it when you see an animal, also you will have to clean it less often which is a good thing. Of course, it protects against damage, as well.

I like them a lot better than the kind that you need to remove completely (various styles which often/usually dangle from scope w/ rubber band when they're removed). There's anotherkind of rubber cover that covers the scope completely. I don''t think that's necessary - I've used my Leupold in the rain many, many times and it has never been harmed. If you were hunting in wet snow or freezing rain it might be a good deal though.

Issues in the rain: droplets on lenses or fog on external lenses (good scopes should not have internal fogging!). I keep a suitable lense brush and cloth on hand to wipe clean. Remember, these are good lenses so you should follow the same care as cleaning a camera lense. This simply means brushing if possible and/or using a lense cloth or a suitable, clean soft cloth. Generally paper is not good for a fine lense, but a soft flannel shirt is.

Issues with the pop-open caps: they are rubber and fit tightly on the scope. Over time, they can tend to show rub marks onthe scope. This is a very minor issue - it doesn't really harm the scope, but if you want your scope to look new/mint in 10 years, it won't. Myself, if I were looking at a used scope with these rub marks, it wouldn't bother me because I'd be putting flip up covers on it again anyway.