Starlight Instruments Cross Design Holographic Attachment for Howie Glatter Laser Collimators

The Self-Barlow attachment is a disc with a white screen on the front and a small built-in Barlow lens in the center of the disc. It is then screwed into the Howie Glatter laser collimator (sold separately) aperture and provides a highly compact method for Barlow-collimating. 

Cross-hair Projection Attachment: Useful for aligning the returning beam on the collimator face.

This pattern is recommended for general use because it can be used with the fastest telescopes likely to be encountered.