ZEELAND, MI (WHTC) - Challenging and deteriorating marking conditions led to a flat quarter, according to Gentex officials. They explained to shareholders and investors in a webcast this morning that third quarter net sales were down 1.3 million dollars from a year ago to 268.2 million, while net income slid four percent to 41.9 million, and earnings per share dropped a penny to 29 cents. For the year thus far, the Zeeland-based manufacturer is showing increases of 10 percent in sales, four percent in income, and three cents per share.