The order is one piece Slim 5u(0.005mm)KA500 linear glass scales/linear encoder/linear sensor, they are KA500-70, KA500-120, KA500-170, KA500-220, KA500-270, KA500-320, KA500-370, KA500-420, KA500-470, KA500-520, you can choose one piece among them.
eBay