Main Street Capital Investor Day Presentation Deck

Headquarters Stevens Point, Wisconsin GAMBER JOHNSON Business Manufacturer of ruggedized docks and mounting systems for electronics Website www.gamberjohnson.com Original Investment Date June 2016 Main Street's View of Transaction and Background Investment Type First lien, senior secured term loan Majority equity investment Transaction Type Management Buyout / Leveraged Buyout ■ Original Capital Invested (1) -$25.0 million senior debt -$15.2 million equity ■ Additional Capital Invested (1) -$57.8 million senior debt -$3.5 million equity (1) MAIN (80%)/MSC Income Fund (20%) Main Street Capital Corporation ■ Gamber-Johnson Overview Founded in 1954, Gamber-Johnson ("Gamber", or the "Company") is a leading supplier of rugged mounting systems that safely secure mobile communication systems, computers, and other electronic equipment in fleet vehicles, public safety vehicles, forklifts, and other mobility applications ■ ■ ■ MAIN ST ■ CAPITAL CORPORATION Robust Platform for Strategic Acquisitions Since Main Street's investment in June 2016, Gamber-Johnson has completed five acquisitions, resulting in product diversification, end-market expansion, and vertical integration The Company's products are used by law enforcement, public safety, military, and warehouse fleets around the globe and are known for being rugged, reliable, and responsive Gamber-Johnson was owned by Leggett & Platt as an independently-operated subsidiary that was non- core to the corporate strategy leaving the management team with minimal capex and operating flexibility Acquisitions include Zirkona (December 2016), Precision Mounting Technologies ("PMT") (January 2017), Premier Mounts (March 2021), InfoCase (August 2022), and Lind Electronics ("Lind") (November 2022) 100% of the capital required to fund the 5 acquisitions came from Main Street, the management team, and internally generated cash flows Established and Enduring Partnerships with Blue-Chip OEMs Highly diversified customer base consisting of blue-chip computer and tablet OEMs/distributors with relationships of 15+ years Blue-chip original equipment manufacturers ("OEMs") include Panasonic, Dell, Samsung, Getac, Volvo, and Zebra, among others NYSE: MAIN Exclusive Access and Rigorous Standards within Industry High barrier to entry due to valuable Intellectual Property and stringent OEM certifications (ISO certified) Gamber-Johnson is one of the two prominent industry leaders showcasing well-established sales channels and widely recognized brand identity mainstcapital.com

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