Use these as adjustable dimmer when looking at the moon. I think adjustment range is 1%-40% . Screw them together or one on the eyepiece and one on the diagonal and rotate the eyepiece for adjustment. Also helps increasing contrast on the planets. Excellent shape except a *tiny* scratch on one of the filters 1/32" long, and it's about 1/4" from the edge, but it doesn't effect anything. Never noticed it until I was about to take a picture of the filters for the ad.
***SOLD*** for both shipped. (paypal +3%) or trade for a TV 8mm or 11mm plossl.