The cells are packaged in single-reaction aliquots. The single-tube transformation eliminates the need to thaw, aliquot,and refreeze cells. The transformation reaction occurs in the tube.

These cells are deficient in all known E. coli restriction systems, preventing the cleavage of methylated DNA. The cells are also endA, improving quality of miniprep DNA, and are recA, improving insert stability. The Hte phenotype increases transformation efficiency of ligated and large supercoiled DNA. It causes production of large colonies. The lacIM15 gene allows blue-white screening.