Tacklife via Amazon offers its Tacklife Advanced Digital Protractor for $24.97. Coupon code "DOS3IMSQ" cuts that to $16.72. Plus, Prime members bag free shipping. That's $33 off and the best price we could find. It features an LED display and auto shut-off and gives relative and absolute angle measurements. Deal ends August 14.

Update: The price has dropped to $22.97 before coupon, $15.39 after.