Usually the people who install it at shops dont screw the mounting bracket in. The reason for this is it makes it easier for thieves to just pull it out and not break anything behind it. If your kit doesnt have mounts to screw it in go find another one that has one. Should cost around $15. You can also use zip ties or straps to hold it in place when you hit bumps or dips. The downside to it is when a theif decides he wants your HU it might damage other parts to your dash as well. Hope that helps.