I ran a WET1000 run for 1 hr. 40 min. seeking 5000A. I had one test wafer at the back of my 7 device wafers and one in front of my device wafers; no empty slots between. Thicknesses averaged 4906A on the back wafer, and 4908A on the front wafer, measured in 5 spots on each wafer. Sharleen Bipin: these are the A and B wafers.