The XLS 21 offers the best "bang for the buck" for pc based time keeping systems. Employees can punch with a PIN number or with a durable proximity badge card (badges sold separately). Multiple communication methods, including RS232 serial, TCP/IP Ethernet, and USB flash drive (drive and cable sold separately), make the XLS 21 a versatile clock, easliy implemented in a wide variety of environments. The included CompuTime101 software offers easy time keeping management.