Bevels were smooth corners, usually on meshless parts. Bevels are 45-degree edges, as formerly seen on the character. Despite its removal, it can still be used with the addition of a feature. However, it cannot be used on materials. The reason for its removal has been brought up in the official Roblox Blog. As stated on the Blog:
"We’ve turned off bevels–they hurt performance and don’t fit our vision for the future look of ROBLOX–and shipped new rendering code that improves performance, particularly in the context of rendering static environments on slow and/or dated hardware."
Read more here.
How To Add Bevels
Bevels can be inserted by adding a SpecialMesh object into the place. The MeshType is set to FileMesh, and the Mesh id to
rbxasset://fonts/torso.mesh. Upon creation, the default values of 1, 2, 2 cause the scale to appear off. To scale it to an appropriate size such as 10, 5, 10, the actual values would need to be a calculation; 10, 5/2, 10/2. This is because the mesh does not auto-scale.