This rugged unit is intended for use in narrow tubes and piezometers. The tape on the skinny dipper is a narrow 0.24 inch x 0.133 inch (6.2 mm x 3.4 mm). The probe is 0.25 inch (6.25mm) diameter stainless steel. This thin section enables the skinny dipper to be used in tubes as narrow as 0.375 inch (9.5mm) internal diameter.