12gauge to 410 conversion

[domxyz]

I found those conversion kit online to go from 12 to 410. Are they worth it? how good are they ?
Accuracy? Spread?

[migrant hunter]

If it's just the chamber adapter(about 3" long) they are fun and quite effective. I'm thinking of picking up a couple for my wife's baikal o/u 12 gauge.
I have used them before and shot skeet with 1/2 oz .410 shells in a 12 gauge.