There's a million labs around so you check with people before you buy. Any capsule is UGL and capped by the lab, 50mg Anavar (var) is becoming more common. It's half life is twice as long as dbol yet guys take 50mg of that at one time regularly.
The only way to tell is use them, the best way is to talk to people, see who's used them before you but them. Look at prices and compare, even though some labs are outrageous on everything, but after you buy them it's too late anyway, not like you can return it.
Another way is to take a cap and break it open, Anavar (var) has a very high melting point, the filler should melt first but it will likely effect the appearance of Anavar (var) also so that might not show you much.
Anavar (var) increase strength very well with literally almost zero sides, no water, so test them out, if you can't tell a difference in a couple weeks, they probably aren't very good. The other issue is tbol and Anavar (var) are similar in the results you will notice, but tbol is liver toxic. If its something I'm getting a lot of, I check meting points, labs, etc to see how they react, but once it's capped it's hard to do unless you are willing to use for a few weeks and have labs, Anavar (var) should be bad on lipids but not much else. It may kill your libido in a couple weeks of solo use though.