+1 what lowbone said. The one you found probably sits in front of lens on the filter thread, they are usually low quality. Don't buy those, waste of money.
I've never heard of any AF Teleconverter for the e mount. MF Teleconverter works fine for MF lenses (especially primes). But used with AF lens, you lose aperture control.
If you have a fast prime, you want 7 element teleconverter with the matching mount. For example, if you have Canon FD mount 50mm f1.4, you want TC with Canon FD mount. The TC sits between camera and lens.
Sony NEX 5N; Panasonic G1/GH2/G3; Nikon D200/D600
SEL1855, Sigma 19+30; Adapted lenses in Canon FD, C/Y, Konica AR, m42, Minolta SR, Nikon F, & Tamron Adaptall mounts