Have an Autoprop on my 410 and got about 1.5knots added speed at 2800 rpm's. It accelerates better, backs down quickly and has virtually no prop walk. There've been several posts over the years about an autoprop not fitting properly because it hits the strut but I didn't have that problem. As far as sizing I'd contact autoprop directly. They got my right the first time around. (see link)They're in the UK Bryce S/V Spellbinder H410
