Is it allowed to work in a company who deal in Audio Visual system, Home Theater and other Security like CCTV and Road Blocker, Barrier etc.

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is established in Islam that in principle all forms of trade are permissible unless there is evidence of being forbidden.

Selling such devices which are used in a permissible manner is permissible unless it is known or there is probable belief that the buyer will use them to do something forbidden. Therefore, working in a company that sells such devices is permissible in principle as long as the majority of the company's activities are permissible in nature.

However, if the company deals in predominantly forbidden activities, like selling these devices to someone who uses them to do something sinful, then it is forbidden to work there.

Allaah Knows best.