Every article of foreign origin (or its container) imported into the U.S., must be marked in a manner that will indicate to the ultimate purchaser the country of origin of the article (see Title 19 of the Code of Federal Regulations (CFR) Section 134.11). The use of the phrase that you suggest, "Made in USA or China," may not allow the ultimate purchaser to know the country of origin of the specific article he/she purchased and, therefore, may not be allowed. Because this is a complicated law with many exceptions and qualifications, we suggest you consult with an attorney on your specific product to determine appropriate labeling.