They do need a housing. Please read below:

Requires NICOR 2-inch Recessed Housing:

For IC-Rated, Airtight, New Construction Housings, use NICOR Model 12200A-LED

For Non-IC Rated, New Construction Housings, use NICOR Model 12201-LED

For Remodel Housings, use NICOR Model 12202R-LED

What is IC rated vs Non-IC rated?

IC stands for Insulation Contact. IC housings must be installed wherever insulation will be in direct contact with the housing. IC rated remodel housings are used in existing ceilings where insulation will be present and in contact with the fixture. Non-IC rated remodel housings are used for existing ceilings where, ideally, no insulation is present.