F18-S
The “S” version is an enhanced or upgraded model.
Improvements over standard F18
Larger transaction log capacity
Updated firmware and algorithm
Better communication compatibility with newer software
Sometimes supports ADMS / Push communication (cloud attendance systems)
More stable SDK/software integration
Typical capacity
Up to 100,000 logs (varies by firmware)
Simple summary
F18 → basic fingerprint access control
F18-i → F18 with integrated card reader
F18-S → improved version with larger logs and updated firmware