The power of Congress to regulate employment conditions under the Williams-Steiger Occupational Safety and Health Act of 1970, is derived mainly from the Commerce Clause of the Constitution. (Sec. 2(b), Public Law 91-596; U.S. Constitution, Art. I, Sec. 8, Cl. 3; "United States v. Darby," 312 U.S. 100.) The reach of the Commerce Clause extends beyond Federal regulation of the channels and instrumentalities of interstate commerce so as to empower Congress to regulate conditions or activities which affect commerce even though the activity or condition may itself not be commerce and may be purely intrastate in character. ("Gibbons v. Ogden," 9 Wheat. 1, 195; "United States v. Darby," supra; "Wickard v. Filburn, 317 U.S. 111, 117; and "Perez v. United States," 91 S. Ct. 1357 (1971).) And it is not necessary to prove that any particular intrastate activity affects commerce, if the activity is included in a class of activities which Congress intended to regulate because the class affects commerce. ("Heart of Atlanta Motel, Inc. v. United States," 379 U.S. 241; "Katzenbach v. McClung," 379 U.S. 294; and "Perez v. United States," supra.) Generally speaking, the class of activities which Congress may regulate under the commerce power may be as broad and as inclusive as Congress intends, since the commerce power is plenary and has no restrictions placed on it except specific constitutional prohibitions and those restrictions Congress, itself, places on it. ("United States v. Wrightwood Dairy Co.," 315 U.S. 110; and "United States v. Darby," supra.) Since there are no specific constitutional prohibitions involved, the issue is reduced to the question: How inclusive did Congress intend the class of activities to be under the Williams-Steiger Act?