Extech sdl350 hot wire thermo anemometer and data logger extech sdl350 the extech sdl350 hot wire thermo anemometer and data logger records data on an sd card in microsoft excel reg format for easy transfer to a pc for analysis the user can manually store 99 readings or set the logger to automatically store up to 20m samples with date and time stamp at a user selected sample rate the sdl3560 measures air velocity using a telescoping probe designed to fit into hvac ducts and other small ope