Bolder Industries has signed a letter of intent (LOI) to merge with blank-check acquisition company GigCapital2 Inc GIX.N in a deal that would take the U.S. sustainable rubber ingredient manufacturer public and value it at close to $900 million, including debt, people familiar with the matter said on Monday. It would be the latest deal by a blank-check vehicle, or special-purpose acquisition company (SPAC), for an environmentally focused business, following mergers for bioplastics company Danimer Scientific and Agricultural technology firm AppHarvest. The LOI is nonbinding but Bolder and GigCapital2 aim to reach a formal agreement before the end of the year, the sources said, cautioning that it is not certain a deal will ultimately materialize. Bolder and GigCapital2 declined to comment. Bolder uses end-of-life tires to develop a sustainable alternative to carbon black material which can be used in rubbers and plastic products. Black carbon is the third-largest contributer of man-made greenhouse gases after carbon dioxide and methane, according to the U.S. Environmental Protection Agency. Bolder is backed by Aravaipa Ventures and I-4 Capital Partners. GigCapital2, which is led by investors Avi Katz and Raluca Dinu, raised $150 million in a June, 2019 IPO. A SPAC is a shell company that uses proceeds from an IPO to acquire a private company, typically within two years. For the private company, merging with a SPAC is an alternative to going public through a traditional IPO.