The Leica 750-model is available in the i-Series, with 2 transmitter mode frequencies (8 kHz and 33 kHz), and the xf-Series, with 4 transmitter mode frequencies (8 kHz, 33 kHz, 512 Hz and 640 Hz). The additional tracing modes allows you to locate underground utilities over greater distances and easily find sewer-camera inspection systems. The 750xf utility locator also has the Mode lock feature. The locator re-starts in the last mode used, saving you time and effort. The xf series lets you use Bluetooth to upload information about the location and direction of the detected utilities to a compatible GIS (Geographic Information System) mapping device (sold separately). You don't have to physically mark the location anymore, which can be useful when working indoors or in a developed area.