X0303 4 2010-08-18 0 0000842633 TRIMAS CORP TRS 0001399771 Valenti Samuel III 39400 WOODWARD AVENUE SUITE 100 BLOOMFIELD HILLS MI 48304 1 1 0 0 Chairman Common Stock 2010-08-18 4 S 0 42000 13.71 D 168000 D Common Stock 2010-08-19 4 S 0 2000 13.69 D 166000 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.50 to $14.02, 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 range set forth in this Footnote. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $13.64 to $13.76, 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 range set forth in this Footnote. /s/ Paula Reno attorney-in-fact 2010-08-20