X0303 4 2009-04-16 0 0000842633 TRIMAS CORP TRS 0001179822 HEARTLAND INDUSTRIAL ASSOCIATES LLC 177 BROAD STREET 10TH FLOOR STAMFORD CT 06901 0 0 1 0 Common Stock 2009-04-16 4 P 0 2996 2.01 A 15236871 I See Footnote Common Stock 2009-04-16 4 P 0 64 2.01 A 15236935 I See Footnote Common Stock 2009-04-16 4 P 0 161 2.01 A 15237096 I See Footnote The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $2.00 to $2.02, inclusive. The reporting person undertakes to provide to TriMas Corporation, any security holder of TriMas Corporation, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnote (1)to this Form 4. These securities are owned directly by TriMas Investment Fund I, LLC ("TIF I"). Heartland Industrial Associates, L.L.C. ("Heartland"), the Managing Member of TIF I, is an indirect beneficial owner of these securities. These securities are owned directly by TriMas Investment Fund II, LLC ("TIF II"). Heartland, the Managing Member of TIF II, is an indirect beneficial owner of these securities. These securities are owned directly by HIP Side-by-Side Partners, L.P.("HIP"). Heartland, the Managing Member of HIP, is an indirect beneficial owner of these securities. Heartland, TIF I, TIF II and HIP may be deemed to be members of a group for purposes of Section 13(d) of the Securities Exchange Act of 1934. Signature by Daniel P. Tredwell, as Managing Member of Heartland Industrial Associates, L.L.C., the Managing Member of TIF I, TIF II and HIP. /s/ Daniel P. Tredwell, Managing Member 2009-04-20