Instruction: Output yes if the supporting document can answer the given question. Otherwise, output no.

Input:
Question: Even with screwing in the lumber, the saw horses are unstable. Any advice before I return and give one star?
Document: I realize that not all lumber is exact in dimension but that does not say much to have 2 brackets break from 1 set. It's plastic, just know that, and not very good plastic either.I give the idea a 5, but these are not worth a five star rating because of the cheap plastic that is used! Guess I'll be going back to my steel saw horses...
I received this product in a timely manner. I purchased the required 2x4 lumber to build them. I made them extra long and extra tall. It comes as a set to make two saw horses.Great product. Easy to build. I think it took me 30 minutes to cut the lumber and built the horses. I would recommend this product.
Compared to my plastic saw horses, these are quite sturdy and look great. Assembly was easy although it is not hard to miss that the top beam is going to be a bit shorter than the bottom one. Once assembled, looks great and is very supportive for my needs. Used a circular saw with them and was able to boards into the saw horse where needed. Seems like a lot of money for plastic but very durable and better than comparable products.
One side of each pair fits the 2x4 perfectly. I had to trim off the excess material from the molds but even then the other side was so snug that I had to plane off 1-2mm on 2 sides of the 2x4 to get it to fit. It didn't matter which 2x4 went in it was still an issue.
Even though they're made of plastic, the finished horse is very solid. Two things to keep in mind. Once you put them together they don't fold up but you can stack them. They don't take up that much room. The other thing is if you want to use treated lumber, you can't. Treated lumber has a slightly larger dimension and won't fit. Standard lumber works just fine. I was going to use lag bolts to assemble them but the included hardware was sufficient.
These brackets provide an excellent framework for the 2x4's. They are very sturdy once assembled. The only reason I didn't give them 5 stars is because the tops of the horses are rough because of the plastic brackets. I imagine you can sand the brackets a bit - I laid towels over them to keep my wood from getting marked. They worked fine.
Seriously, 2x4s did not fit in them. The demensions must be wrong. If treated lumber is bigger, then my bad. I sanded the 2x4s down and pounded and pounded with a rubber mallet. It must have taken 2 hours.But, when done, saw horse is super solid.For a bunch plastic, it seems this product should be priced around $10.
I always have various projects going on around my house and now I can finally get off the ground with my miter saw and table saw. Being able to quickly change the height and width of these sawhorses is an attractive feature, but I don't think its something I'll need very often. Even with purchasing the 2x4's, you'll still be way under the cost of another set of sawhorses.
I think a fair price would be something around $15 dollars. I'll admit they are easy to use, however building a saw horse is not that complicated. A quick search on youtube will provide you with some excellent simple steps to accomplish the same thing even without cutting angles.If you want something that is as easy as could be, quick, uses a minimal amount of wood, and sturdy these fit the bill.
I made  a table using these saw horses. They are 4 pieces (2 sets). They are not fancy but the directions could have been a little more clearer.
Answer: yes