High-capacity 4000mAh lithium-ion battery ensures extended usage for Samsung GALAXY A40 A405F with stable power output. Precision-engineered cells with advanced circuit protection prevent overcharging, overheating, and short circuits. Seamless compatibility with original device connectors for plug-and-play installation. Ultra-thin 8.4mm design maintains smartphone"s sleek profile without adding bulk. Grade A battery cells deliver 500+ charge cycles while retaining 80% capacity. Ideal for business travelers needing reliable backup power or students requiring all-day performance. OEM-equivalent quality with CE/FCC/RoHS certifications for guaranteed safety. Optimized energy density provides 22% longer standby time compared to standard replacements. Perfect solution for bulk procurement by mobile repair shops or corporate IT departments.