This filter will suit a 150mm telescope, It is for
IMAGING ONLY not visual observing. The dimensions are as follows
Open aperture 137mm
Inside Diameter 168mm
Overall Diameter 173 mm
Used once as I upgraded to a 180 Mak for solar imaging.
See my post for images taken with this filter
http://www.iceinspace.com.au/forum/s...d.php?t=187893
$60 posted Australia wide