With the KEH sale today. Got 25% off a LN- TC-14E II teleconverter. That will work with my 600mm f/4.0 AF-I lens. I posted the sale link in equipment since it's a mix of everything for the 25% off items. I ended up keeping the TC-14E III as it did work with a couple of my newer lenses. And it will work for future lenses if I upgrade in the future. I will probably put the II series in the 600mm box and just leave it with it all the time.