When sourcing a flatlock machine (also known as a coverstitch machine), you must prioritize the number of needles and threads (typically 3-needle 5-thread or 4-needle 6-thread for seamless activewear). Ensure the machine features an integrated direct-drive motor to reduce energy consumption by up to 70% and minimize vibration. Look for automatic functions such as thread trimming, foot lifting, and needle positioning to increase production efficiency. Additionally, verify the maximum sewing speed, which should ideally reach 5,000 to 6,000 stitches per minute (RPM) for high-volume manufacturing.