This is a fabulous product. Fits perfectly and doesn't come off of the housing or the camera. It's super useful and helpful. When I charge the battery, I cover the lens with the small circle and have no worries. I also love knowing the lens part of my housing is always protected. A must buy for all GoPro owners!
Both are a decent quality of plastic. I was a little upset that the inside of the large cover was just plastic so basically it's plastic against your GoPro case considering it's not a tight fit with it being plastic and sitting in your luggage it does have the ability to vibrate against the cover.
Fit my Gopro Hero 3 great. It is tight enough that it will not fall off, I hold my Gopro and ran my 2013 Honolulu marathon and use the cover to prevent my lens area got wet when I am not shooting, it works really well. Wish it is a little cheaper.
I only wanted to round cap lens cap to put on the go pro when it was not in the water proof casing. That part fit perfectly! It was snug enough to not pop off unlike the square cap for the waterproof case. I never use that because it really doesn't fit. Sadly, I misplaced the round cap so I can't use that anymore.
I must admit, I payed next to nothing for this cover. However, it is disappointing when a simple product does not fit properly. It fits loosely around the lence and I am afraid it will come off rather easily. So, u get what u paid for.