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EXHIBIT 99.3
[LETTERHEAD OF MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED]
CONSENT OF MERRILL LYNCH, PIERCE,
FENNER & SMITH INCORPORATED
We hereby consent to the inclusion of our opinion letter dated September
30, 2000 to the Board of Directors of MKS Instruments, Inc. ("MKS") as an Annex
to the joint proxy statement/prospectus relating to the proposed merger of MKS
and Applied Science and Technology, Inc. and to the references thereto in such
joint proxy statement/prospectus under the captions "SUMMARY --- Opinions of
Financial Advisors" and "THE MERGER --- Opinion of MKS' Financial Advisor." In
giving this consent, we do not admit that we come within the category of persons
whose consent is required under, and we do not admit that we are "experts" for
purposes of, the Securities Act of 1933 and the rules and regulations
promulgated thereunder.
New York, New York
November 13, 2000
/s/ Merrill Lynch, Pierce, Fenner & Smith Incorporated
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MERRILL LYNCH, PIERCE, FENNER & SMITH INCORPORATED
