Replace C9.25 Vixen dovetail to CGE/Losmandy dovetail

[MarkSix]

[Solved]

It turned out to be a 3.5mm HEX Key which  I of course did not have (I have a couple of hexkey sets but no one had the 3.5mm size).
Fortunately I found one hardware store open on sundays that had the 3.5mm. 

 

Hi guys. 
I have a Celestron C9.25 A XLT Optical Tube with Vixen type dovetail that a bought together with a  Celestron Advanced CG5-GT mount av couple of years ago. Now I have bought a Celestron CGEM DX mount and i would like to replace the Vixen style dovetail on the C9.25 Optical tube to a CGE/losmandy dovetail. But I need some information on the size of the hexscrews  (hex tool size prefered).  My problem are the two hexscrews that fit the dovetail to the optical tube at the back of the scope. I need to know what what hex tool size is.
The screw that fits the dovetail at the front of the tube was no problem. Sorry if it is stupid question but it it  feels better to be sure before I make the visit to the hardware store.

 

 // Jarmo