Need help picking a red dot scope for this gun?

I have a vp5 ras gun and it has a special way to hold red dot scopes. It doesn't use a rail, its hard to explain here.





that black thing on top is whats on my gun, and i was wondering if you guys know a red dot scope that will work from this.
Please, from airsoft gi. thanks

a red dot green dot scope would be awesome too, any ideas anyone?

I belive that mount can removed. But types of red dots anything that has a 30mm tube so that opens up a wide variety of scopes like....

This B-2 Red/Green aimpoint
http://www.airsoftgi.com/product_info.php?cPath=36_117&products_id=2826

or like this B-2 Red/Green combat point
http://www.airsoftgi.com/product_info.php?cPath=36_117&products_id=2348

or this G&P red dot
http://www.airsoftgi.com/product_info.php?cPath=36_117&products_id=1614

So theres three from ASGI im sure if you look else where you will also be able to find something.

if you take the mount off there is a special red dot theres 2 but they are diffrent costs http://ebaybanned.com/product_info.php?cPath=32&products_id=1342 and http://www.airsoftpost.com/matrix-mod5-aluminum-real-steel-scope-built-claw-mount-p-26707.html