What is the temp range on this unit? Need 260 degrees Celsius. Thank you.

A USB device would be unsuitable for temperatures as high as 260C. You would need something such as the Sensatronics U4 and a high temperature oven probe for this type of application. 

If you require a handheld thermometer with a probe take a look at the ETI models such as the 2003, which has a range up to 1000C.