Thank you for writing.
Your findings are correct. We do provide two sets of assemblies, one build for .NET versions prior 4.0 (that would be Bin) and one built for .NET 4.0 and above (that would be Bin40). Depending on your project's Target Framework, you would pick the right Telerik assemblies for the purpose.
You can also identify whether an assembly is 2.0 or 4.0 by looking at their version suffix - 2.0 will end up with .20 e.g. 2015.1.331.20
and 4.0 will end with .40 e.g. 2015.1.331.40.
That’s pretty much all you need. The most important thing is to never mix .20 and .40 assemblies in the same project, as this might cause issues.
I hope that you find this information useful. Should you have any other questions, do not hesitate to contact us.
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