In August 1999, a demonstration study was conducted to verify the performance of six groundwater sampling devices: Multiprobe 100 (multi-level sampler, Burge Environmental, Tempe, AZ), SamplEase (bladder pump, Clean Environment Equipment, Oakland, CA), Well Wizard dedicated sampling system (bladder pump, QED Environmental, Ann Arbor, MI), Kabis sampler (discrete-level grab sampler, Sibak Industries, Solano Beach, CA), GoreSorber Screening Survey (diffusional sampler, W. L. Gore and Associates, Elkton, MD), and the Micro- Flo sampler (bladder pump, Geolog, Inc., Medina, NY). This report contains an evaluation of the Micro-Flo bladder pump. A brief outline of this report is as follows: Section 2 contains a brief description of the Micro-Flo bladder pump and its capabilities. Section 3 outlines a short description of the test facilities and a summary of the verification test design. Section 4 includes a technical review of the data, with an emphasis on assessing overall sampler performance. Section 5 presents a summary of the Micro-Flo sampling device. Appendix A contains performance data for the reference pump and Appendix B provides an assessment of quality control data associated with the analytical method used in this study.