I have to agree with Tom, it is pretty hard to beat the accuracy of a 20" dial that you can buy for about $10 - no batteries, no magnetic interference from metal scope parts, no worries about magnetic declination.

Tom's Wixey inclinometer at $40 is a great value too, less than half the cost of the SmartTool that I used.

A $50 system with electronic altitude accurate to .1 and azimuth accurate to (conservatively) a half degree is a very cheap and precise set up- less than half the cost of encoders alone for a DSC system!

Rod