I looked far and wide and came across many other products and read many marginal to negative reviews that I could relate to and had the same issue: moisture damage to the nano. I had a 3rd gen nano that lasted me a long time (~6 years) and used an Incase armband to workout. I do it all: lift weights, run, bike, row, etc. I think the activity that caused the most damage was running since it just makes me sweat more. I would wear it on my upper arm. The neoprene on the Incase unit was thick on the wrap, but only a thin layer stood between my skin and the nano. Over time, the sweat ate away at the corners and the bottom of my device, not to mention the stinkage it gloriously bestowed to the armband. Well my 3g nano finally died and I got the 7g, great device.
Negatives from other makes: Griffin and Belkin types, same thin single layer of protection, no access to side buttons, big gap on the Griffin. Roocase and others: can't clip it upside down since nano would slide out, based on reviews. Other cheap ones: material and clip is flimsy. So I took a gamble on this one and I hope this helps others that have my same needs and concerns.
This product is two pieces: the green silicone cover and the black, hard plastic holster. The green cover wraps around the entire nano, save for the screen. Next, you slide the covered nano into the holster. You will notice that there is a tab at the top of the holster to lock it into place. Once locked in, you have no problems using the side buttons. Folks may wonder how the heck can you use this clip in the same fashion as an armband. Well duh, a regular ol' sweatband!! It's cheap and you can wash it to remove any stinkage. Buy a three pack for cheap and you're set. My old Incase would only last a couple of uses before it would start stinking again. Even after washing, it would still have some residual odor. The clip is very sturdy and will clamp onto anything very securely.
My experience exercising: I clipped it upside down because it is easier to view the screen, just my preference. Whether upside down or regular, your sweaty hands will not get onto the nano when touching the side buttons. I just put it on shuffle and let it play. I don't use the touch screen when running. After the workout, the sweatband was wet, obviously, but the only other thing had a little moisture was the back of the plastic holster. Nothing on the green silicone and most importantly, absolutely nothing on the nano! You effectively have 3 layers of protection between your skin and the nano. That is very assuring.
I highly recommend this product, I just didn't want to wait 1 to 2 months? for this to ship. I was fortunate enough to find this at a local store. Maybe a review like this and maybe more will make some of these more readily available here; I believe the company is from Australia. Anyways, I hope this helps someone.