are these to reduce light glare when one's viewing through a scope or to reduce reflected light in the OTA?
A 30cm foam shield like the dew shields here
http://www.atozastro.com/shop/script...?idCategory=25 as well as internal flocking would reduce reflected light into the OTA as light from streetlamps or roof fitted lamps are quite high up, but won't stop one being blinded say by a passing car.