Exhibit 99.1350CERT


     Certification Pursuant to Rule 30a-2(b) under the 1940 Act and
                  Section 906 of the Sarbanes Oxley Act


Pursuant to 18 U.S.C.  1350, the undersigned officer of BlackRock Small Cap
Growth Fund II of BlackRock Series, Inc. and BlackRock Master Small Cap Growth
Portfolio of BlackRock Master LLC (together, the "Registrants"), hereby
certifies, to the best of his knowledge, that the Registrants' Report on Form
N-CSR for the period ended May 31, 2007, (the "Report") fully complies with
the requirements of Section 15(d) of the Securities Exchange Act of 1934, as
amended, and that the information contained in the Report fairly presents, in
all material respects, the financial condition and results of operations of
each Registrant.


Date: July 24, 2007


/s/ Robert C. Doll, Jr.
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Robert C. Doll, Jr., Chief Executive Officer of
BlackRock Small Cap Growth Fund II of BlackRock Series, Inc. and
BlackRock Master Small Cap Growth Portfolio of BlackRock Master LLC



Pursuant to 18 U.S.C.  1350, the undersigned officer of BlackRock Small Cap
Growth Fund II of BlackRock Series, Inc. and BlackRock Master Small Cap Growth
Portfolio of BlackRock Master LLC (together, the "Registrants"), hereby
certifies, to the best of his knowledge, that the Registrants' Report on Form
N-CSR for the period ended May 31, 2007, (the "Report") fully complies with
the requirements of Section 15(d) of the Securities Exchange Act of 1934, as
amended, and that the information contained in the Report fairly presents, in
all material respects, the financial condition and results of operations of
each Registrant.


Date: July 24, 2007


/s/ Donald C. Burke
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Donald C. Burke, Chief Financial Officer of
BlackRock Small Cap Growth Fund II of BlackRock Series, Inc. and
BlackRock Master Small Cap Growth Portfolio of BlackRock Master LLC



This certification is being furnished pursuant to Rule 30a-2(b) under the
Investment Company Act of 1940, as amended, and 18 U.S.C. Section 1350 and is
not being filed as part of the Form N-CSR with the Securities and Exchange
Commission