Described herein, among other things, is an adapter comprising a population of first oligonucleotides, a second oligonucleotide and a third oligonucleotide, wherein the first oligonucleotides, the second oligonucleotide and the third oligonucleotide are hybridized together to produce a complex that comprises: (i) a first end comprising a transposase recognition sequence, (ii) a central single-stranded region of variable sequence and (iii) a second end comprising sequences that are non-complementary. A method, as well as a kit for practicing the method, are also provided.