Following the successful evaluation of the demonstrator SMB1H, SMRT Buses placed an order for 66 initial production units, known to bus enthusiasts as Batch One. They were registered SMB2E to SMB67T. All units were assembled by the Thailand-based Thonburi Busbody, with the bodywork supplied by Gemilang Coachworks of Malaysia.

The OC500LE was the first wheelchair-accessible bus (WAB) introduced by SMRT Buses. Launched in 2008, It featured the improved OM457hLA turbocharged engine (11,967cc) with the ZF 6HP 592C Ecomat six-gear automatic transmission. Selective Catalytic Reduction (SCR) technology was used for exhaust treatment, which requires the use of AdBlue to meet the stringent emission standards. The Lawo BENEFIT EDS (orange colour) is LED-based and now standard within the industry, replacing previous flip-dot models. A new interior scheme that would become the standard of new SMRT buses and future refurbishments was adopted, and each OC500LE was installed with Konvekta air-conditioning unit.