Traditional labels can virtually hide books that are shelved out of  order.
ColorMarq reveals mis-shelved books with visual scanning as well as incidentally when browsing.
"I am impressed with the system's elegance in its simplicity and its potential to revolutionize library shelving practice. You have my admiration for developing a truly innovative solution to the problem of mis-shelved books in libraries.”  William J. Hubbard - Author of “Stack Management”