The NEBNext Ultra II Ligation Module has been optimized to ligate efficiently DNA adaptors compatible with Illumina sequencing to end-repaired, dA-tailed DNA fragments. The module is optimized for use with the NEBNext Ultra II End Repair/dA-Tailing Module (NEB #E7546), and is part of the Ultra II DNA workflow which enables high yield preparation of high quality libraries from 500 pg to 1 µg of input DNA.