Hi,
Looks like a Apple Keyboard with Numeric Keypad, model A1243, order number MB110LL/A, MB110LL/B. It was introduced in August 2007 and discontinued in June 2017. It should have a 13 digit serial number on the "USB ledge/foot", and have the model number A1243 in the printing across the bottom edge on the back.
As an FYI, the key caps and scissors for these keyboard do sometimes change slightly during production, so any you may purchase may not fit correctly.
C