Exit for Copying Customer Material Description to Material Description in Sales Order

Hello Experts

Requirement : Exit for Copying Customer Material Description to Material Description in Sales Order as soon as Equipment number is entered in KDMAT field

I will be entering the Equipment number in Contract the text should get copied to material text .

is I want KDMAT - Text to be copied to VBAP-ARKTX field which will have default Material description .

Regards

Rohit