Sensors of temperature and salinity (conductivity) could by of two types (SBE-41 and FSI). Lets note that the drift of the salinity values could be up to 0.01 PSU after two years from time of float deployment.

APEX (WEBB) uses alkaline batteries, PROVOR uses lithium. APEX is easy to ship, there are no restrictions. Lithium batteries are restricted for shipment - for example, they must go by CARGO (non-passenger) aircraft only. The APEX user-interface is very simple, so sailors with little training can do it. To turn the float ON, technic passes a magnet over a marked location on the hull. The float does a self-test, then it is deployed at the surface.

The PROVOR interface is much more complex, with a large number of parameters that must be entered, from a terminal, just before deployment.

The preventage of PROVOR float was different levels of drift and the lower level of measurements (for APEX they are the same). At the end of cycle PROVOR float sinks to the 2000 m level and from it the float begins measurements. Now WEBB Co produces suchfloats too.

Deployed float drifts at the surface during about 6 hours. It sends on one of satellites all data. After it the float goes to the level of 2000 m during some hours. At the level the float drifts during 10 days. After it the float goes to the surface with the measurements of temperature and conductivity during about 6 hours. Cycle repeats until battery will work or fishermen catch it.