AutoMechanic, that's what the website says:
"The chrome molybdenum construction and black phosphate coating make each of the sockets in this deep impact socket set durable and rust-resistant." Source:
www.harborfreight.com
"This high quality impact socket set is durably constructed of rugged chromium molybdenum ..." Source:
www.harborfreight.com
The Icon line is also Cr-Mo:
www.harborfreight.com
Speaking of Icon, is there any practical advantage of the Icon over the Pittsburgh impact sockets?
"The chrome molybdenum construction and black phosphate coating make each of the sockets in this deep impact socket set durable and rust-resistant." Source:

1/2 in. Drive Metric Impact Deep Socket Set, 13 Piece
Amazing deals on this 13Pc 1/2In Dr Metric Deep Wall Impact Socket at Harbor Freight. Quality tools & low prices.
"This high quality impact socket set is durably constructed of rugged chromium molybdenum ..." Source:

1/2 in. Drive Metric Impact Socket Set, 13 Piece
Amazing deals on this 13Pc 1/2In Dr Metric Impact Socket Set at Harbor Freight. Quality tools & low prices.
The Icon line is also Cr-Mo:

1/2 in. Drive Metric Professional Impact Socket Set, 14 Piece
Amazing deals on this 14Pc 1/2In Dr Metric Impact Socket Set at Harbor Freight. Quality tools & low prices.
Speaking of Icon, is there any practical advantage of the Icon over the Pittsburgh impact sockets?