Blast gates can be used to shut off the airflow to part of your ducting run. For instance, if you have one outlet for your air scribes and another for air abrasives, you can shut the blast gate and extract the air from one of those areas at a time. By closing off inactive lines, you maximise the airflow along the active line. 

The centre plate simply slides between the open and closed position and can be locked in position. 

The blast gate can be mounted using a bracket (sold separately) which can be wall or table mounted in any orientation. 

This blast gate has two 125mm male spigots, and fits into 125mm female fittings such as galvanised ducting, female-female couplers and can also be used with 125mm flexible ducting.