I have obviously confused the hell out of everyone who has read the above ad.
What I meant by one screw was the screws that hold the Acog to the base of the TA-51.
Not the screws that clamp to the rail.
So If you have a TA-31 or TA-01 which come with one carry handle screw you would have two to secure it to the TA-51 with.
Trijicon is charging $15 for them or so Ive heard.So I thought I would include the extra to sweeten the deal.