The Board held that the respondent union violated its duty to “confer in good faith with respect to wages, hours, and other conditions of employment * * *” imposed by section 8(b) (3) and 8(d) of the National Labor Relations Act, 29 U.S.C. § 158(b) (3) and (d) when it refused to enter into a collective bargaining agreement unless that agreement contained a provision requiring the employer to post a performance bond.
The respondent first contends that the evidence does not support the Board’s finding that the respondent insisted upon the posting of a performance bond. We think that the record considered as a whole contains substantial evidence to support the Board’s finding. See Universal Camera Corp. v. NLRB, 340 U.S. 474, 71 S.Ct. 456, 95 L.Ed. 456 (1951).
The respondent next contends that the Board erred in concluding that bargaining for the performance bond clause did not constitute bargaining “with respect to wages, hours, and other terms and conditions of employment” within the meaning of section 8(d). See NLRB v. Wooster Division of Borg-Warner Corp., 356 U.S. 342, 349, 78 S.Ct. 718, 2 L.Ed.2d 823 (1958).
The Board has uniformly held that bargaining for a performance bond does not fall within the meaning of section 8(d), and that, therefore, the par*57ties may not insist upon such a bond to impasse. These orders have uniformly been enforced, despite challenge. The cases are collected in NLRB v. American Compress Warehouse, 350 F.2d 365, 370 n.7 (5th Cir. 1965), and NLRB v. Davison, 318 F.2d 550, 555 n.14 (4th Cir. 1963). The basic reason for these rulings was expressed in Excello Dry Wall Co., 145 N.L.R.B. 663, 664 (1963): “The statutory obligation to bargain is not limited and cannot be limited to financially responsible parties, whether employer or labor union.”
In the present case the Board did not hold all performance bond clauses to be nonmandatory subjects of bargaining. Respondent had argued to the trial examiner that the performance bond it had sought was different from those involved in the Board’s earlier decisions because it was to be a cash bond (rather than a surety bond), and because it was to be conditioned solely upon payment by each employer of the Wages and other benefits due its employees. The trial examiner expressly reserved the question of whether such a performance bond clause would have been a mandatory subject of bargaining. He pointed out that the clause involved in this case would have required the contracting employer to pay liquidated damages and to guarantee payment of wages and fringe benefits due the employees of subcontractors of the contracting employer. The trial examiner held: “a contract which includes an obligation to pay wages of another employer’s employees or to pay damages for nonperformance of an employer’s obligation * * * would be a nonmandatory subject of bargaining.” International Hod Carriers, Local 1082, 150 N.L.R.B. 158, 178 (1964). The Board adopted this conclusion.
“Obviously, classification of bargaining subjects as ‘terms or conditions of employment’ is a matter concerning which the Board has special expertise.” Local Union No. 189, Amalgamated Meat Cutters and Butcher Workmen of North America, AFL-CIO v. Jewel Tea, 381 U.S. 676, 685-86, 85 S.Ct. 1596, 1600, 14 L.Ed.2d 640 (1965) (opinion of Justice White). We are not convinced that the Board erred in the exercise of that expertise here.
The order of the Board will be enforced.