Transgenic construct used to study interactions between insulator sequences. Consists of 10 UAS sites, an FRT cassette containing four copies of the third su(Hw) binding site from the gypsy insulator (gypsy\su(Hw)BR), the y transcription unit, a loxP cassette also containing four copies of the third su(Hw) binding site from the gypsy insulator and the mini-w gene.