Code for a Texbox Item for input of Purchase Orders

[Fireeyes2l2]

I have just started picking up VBA and I am using Excel 2007. I am creatin g a UserForm that has multiple textboxes for data input. One I am having trouble with, is verifying that the input to the Purchase Order textbox is correct. I am wanting the user to input a PO in the format of "JK 12345" -> Two Letters followed by a space then Five Numbers. Does anyone know how this may be done? Thanks in advance.

[Solus Rankin]

If TextBoxN like "[A-Z][A-Z] [0-9][0-9][0-9][0-9][0-9]" then finish code...