CVHD-950 and CVHD-950X

Is any one know the different between Crystek CVHD-950 and CVHD-950X?
Thank you.

Hi and welcome to the Digikey tech forum. The difference is the operating temp range, refer to page two on the datasheet you will see the X is for -40°C to +85°C , without the X it is 0°C to +70°C (standard).