Im pretty sure its for any glass mate, inside and out. In fact i think its actually designed for windscreens primarily. Used it on all my cars with excellent results. Also prevents steamy windows on the inside and makes the wipers run silky smooth. It makes them so smooth that the windows feel like glass.

Having said that, i dont use it on the escos because its not needed as the centre of my windscreen hasnt even seen a wiper for about 10 years at least.