The 100 bp DNA Ladder is suitable for sizing double-stranded DNA from 100 to 1,500 bp. Prepared from a plasmid containing repeats of a 100 bp DNA fragment, the ladder consists of 15 blunt-ended fragments ranging in length from 100 to 1,500 bp, at 100-bp increments, and an additional fragment at 2,072 bp. The double-stranded ladder can be visualized on 1% to 2% agarose gels after ethidium bromide staining. For easy reference on agarose gels, the 600- bp band is two- to three-times brighter than the other bands in the ladder. This ladder can be stained with ethidium bromide or radiolabeled using T4 polynucleotide kinase or T4 DNA polymerase.