The OKI Microline 3321eco prints sharp mono text at 435 cps with 240×216 DPI, using a robust 9‑pin head that lasts 200 million characters. Built‑in Code 128 and UPC barcodes add versatility, while Energy Star certification keeps power low. USB, parallel, serial and optional Ethernet support Windows Server environments, and quiet mode stays under 52 dB for a calm workspace.