help with this tut on rockslide

[ATTACH]121468[/ATTACH]i followed this tut here

http://www.packtpub.com/article/getting-started-with-blender-particle-system-2?sr

see file

but the rocks falling from the group are super small!
whre can we change the rock size from the group?

Thanks for any help

Open the physics TAB. You have the size set very small.