March 21, 2005 – Entegris Inc. and Mykrolis Corp. today announced a definitive agreement to combine in a merger-of-equals transaction that creates a combined company valued at approximately $1.3 billion. The combined company, which will be known as Entegris Inc., will have combined trailing annual sales of more than $650 million.

Upon completion of the transaction, which needs shareholder approval and is expected to occur in 3Q05, current Entegris shareholders will own approximately 56% of the combined enterprise and current Mykrolis shareholders will own approximately 44 percent.

The new Entegris will be headed by Gideon Argov, currently CEO of Mykrolis, as chief executive officer, with James E. Dauwalter, currently CEO of Entegris, serving as non-executive Chairman of the Board of Directors.

Entegris has approximately 1800 worldwide employees and Mykrolis approximately 900, both excluding temporary workers. The companies have identified approximately $15 million in annual cost savings, to be achieved principally through the rationalization of duplicative administrative functions and facilities. It is expected that approximately 5% of the combined company’s work force will be affected by the merger. Necessary staff reductions will be achieved through normal attrition wherever possible.