If you put "Tracker" in the Search box on the top right side of the page it should bring up the answers and comments I received to a similar question I posted a few months ago. I never did fit one because in a fit of greediness I sold my Defender and bought a Discovery.I'm in search of a tracker for both my D90 and series, especially having had a few stolen in my area quite recently. Anyone have any recommendations for a tracker and if it affects insurance?