Already in TF2

Skybox Name Map Credit Total
sky_day01_01 sky_day01_01
(HDR)		 box · black_void · dark_room · stage · stage_big Valve 5
sky_dustbowl_01 sky_dustbowl_01
(HDR)		 afd_warehouse · character_lighting_map · mtt_heavy Valve 3
sky_well_01 sky_well_01
(HDR)		 cloak Valve 1
sky_granary_01 sky_granary_01
(HDR)		 mtt_soldier Valve 1

New

Skybox Name Map Credit Total
sky_day02_02 sky_day02_02
(HDR)		 devtest Valve 1
sky_mtt_engineer_01 sky_mtt_engineer_01
(HDR)		 mtt_engineer* Valve 1

*This map uses the HDR skybox.