Construct designed for use in a single-strand annealing (SSA) assay. Contains two copies of a mini-w gene in tandem, with an RS(I-SceI) site in between the two copies. The copy downstream (3') of the RS(I-SceI) site is functional. The upstream (5') copy is non-functional due to deletions of the first 52bp (including the ATG) and the last 3.0kb (3' end of the coding sequence and 3'UTR).