Qu: Solutions for retrofitting recessed lighting

Does anyone know if you want to retrofit a home that currently has recessed lighting, if you can get a recessed light product that is already sealed? The house in question has failed its blower-door test due to the amount of air that is going up through the roof due to the recessed lights.

This website: <http://oikos.com/library/airsealing/recessed_lights.html> seems to imply that you can, but does anyone know who sells these? Has anyone had any experience with them?