These pants are pretty much what they say they are: bright yellow/green mesh with two reflective bands. The bottom of the leg is elastic. The waist is elastic and has a drawstring. The build quality doesn't seem amazing (very much single-stitched, etc.) to me but it's fine for visibility-wear. This type of clothing must be worn over your regular clothing. It is very meshy.
My bone with this product is the size. I stand 5'8" and medium build. I debated between a medium and large and decided to go with large after reading about sizing of this type of clothing elsewhere. It turns out there's no such thing as size large in this product. It's size L/XL and it is absolutely enormous. It goes almost to my armpits. I can't imagine who would be tall enough to need a size that is even larger than this. It's also very big around. My pants would easily accommodate someone standing at 6'7" and weighing 300 pounds or so. For whatever reason I went ahead and wore them once on my bike, thinking the size wouldn't matter much. But they are so billowy they kept getting stuck in my chain and on other parts of my bike. I don't feel right returning them in this state.
So anyway, since there is no size information, unless you are very tall and/or big around, get a medium, which I expect is actually a M/S. I suppose if you are wearing very heavy rain/snow pants under this and you are tall, they would also work.
Next time I get a product and it's clearly many sizes too large I'm sending it straight back instead of giving it a try.
By the way, I ordered this along with several other items and it came at least two weeks later. Very slow.