A substrate processing apparatus comprising: a frame; and at least one substrate transport arm connected to the frame, the at least one substrate transport arm having at least one end effector, each end effector having a base portion configured for coupling with a respective substrate transport arm, a first and second substrate support tines (350T1, 350T2) mounted to and dependent from the base portion where at least one of the first and second substrate support tines is movable relative to the base portion, each of the first and second substrate support tines having respective substrate contacts (800A-800D) configured to contact and support a substrate held by the end effector between the respective substrate contacts of the first and second substrate support tines at a substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines, and an end effector drive section configured to vary a distance between the first and second substrate support tines relative to each other on the fly and change the substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines from a first substrate support seat dimension span to a different second substrate support seat dimension span. a frame; and at least one substrate transport arm connected to the frame, the at least one substrate transport arm having at least one end effector, each end effector having a base portion configured for coupling with a respective substrate transport arm, a first and second substrate support tines (350T1, 350T2) mounted to and dependent from the base portion where at least one of the first and second substrate support tines is movable relative to the base portion, each of the first and second substrate support tines having respective substrate contacts (800A-800D) configured to contact and support a substrate held by the end effector between the respective substrate contacts of the first and second substrate support tines at a substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines, and an end effector drive section configured to vary a distance between the first and second substrate support tines relative to each other on the fly and change the substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines from a first substrate support seat dimension span to a different second substrate support seat dimension span. a base portion configured for coupling with a respective substrate transport arm, a first and second substrate support tines (350T1, 350T2) mounted to and dependent from the base portion where at least one of the first and second substrate support tines is movable relative to the base portion, each of the first and second substrate support tines having respective substrate contacts (800A-800D) configured to contact and support a substrate held by the end effector between the respective substrate contacts of the first and second substrate support tines at a substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines, and an end effector drive section configured to vary a distance between the first and second substrate support tines relative to each other on the fly and change the substrate support seat dimension span between the respective substrate contacts of the first and second substrate support tines from a first substrate support seat dimension span to a different second substrate support seat dimension span.