Our quilt guild had a demo of the log cabin trim tool last month. There are some limitations on the size of the log cabin block it will deal with. It is good for trimming up log cabin blocks as-you-go. I believe the one pictured in this thread works for log cabin blocks up to 8". There is another tool for larger blocks -- maybe 12"? Anyway, I ended up not buying it just because I realized that not only do I not need it (have not had a problem so far with log cabin blocks turning out wonky or not to size), it adds an extra step to each log. I'm more in the speed-piecing/strip-piecing category of quilters so, for me, this tool would probably have sat in my someday-I-will-have-to-try-this-out drawer for gadjets I have bought over the years.