Isn't this just a single leg off a pair of yoga pants?

If you steal a dwarfs yoga pants it may just work.

My son's bicep measures 15" around. i'm wondering if the nylon with grip in size large will be too snug. anyone have any advice please?

All of our sleeves stretch, the size chart that we have on our images is not the circumference of your arm or the sleeve but the flat measurement of the sleeve over a table so you need to double that. For example, lets say you want one of our HYBREED sleeves (nylon) if your wrist is about 6 inches of circumference, and your bicep has a circumference that is around 12 inches, you should probably go with the size MEDIUM, because if you see the size chart it says that our medium sleeve has 3 inches on the wrist (flat) and 5 1/8 inches on the bicep (also flat), if you double that the wrist would be 6 so is a perfect fit and for the bicep its 10 1/4, you will be two inches above but since they stretch is also a perfect fit! With 15 inches we recommend going with a size Medium for a tight fit or Large for a regular fit. Hope this would help!

I want to order the hybreed where can I select this?

Hi! We are currently out of stock on our Hybreed sleeves, we're doing our best to have them restock ASAP! :) We expect to have them in stock on amazon in the next few weeks.

How long does it take for the sleeve to start stretching and lose compression over time?

We tried with different materials, and different combinations just to reach the results that our sleeves have right now (for both of our series) and so far we have not had any problem like that. Even though we tested them before we launch our brand, We keep using our product on regular basis and our sleeve is still with the same compression. So you can rest assured that your sleeve will be with the same quality for a very long time in all of your gaming sessions.