The Good
This antibody is very specific and produces a band for the full-length (240kDa) and break down product (140kDa).
The Bad
Running your sample on a gradient gel (4-12%) does produce two bands very close to the same 140kDa molecular weight for the spectrin break down product (see image).
The Bottom Line
This antibody is very good for the WB analysis of calpain activity because it only recognizes alpha-spectrin.