Buyers should prioritize audio output quality (SNR > 85dB) and storage capacity, typically supporting TF/SD cards up to 32GB or 64GB. Ensure the device supports multiple formats like MP3, WMA, and WAV. For battery-operated models, look for a lithium battery capacity of at least 500mAh to ensure 4-6 hours of continuous playback. If the product is a DIY or craft component, verify the trigger mechanism (e.g., light sensor, button, or motion sensor) and the speaker wattage (typically 0.5W to 2W) for clear resonance within the box.