III does not have any recommendations pertaining to the printers for use with the Polaris software. If you're unsure what printer to purchase, III would recommend conferring with other libraries to ascertain what works for them.
Customer operating environments vary with respect to equipment models, operating system versions, firmware/driver levels and other underlying third-party software components. These variances may affect the compatibility of Receipt Printers. Compatibility may also be affected any time that a manufacturer of equipment or software utilized in the operating environment issues an update, such as a revised hardware model or a firmware or driver update. Third-party printers in the Customer's specific operating environment are the Customer's responsibility.
Leap uses browser-based printing, so should function with any printer that is able to print to the local device, as it is entirely using the device's/browsers printer settings.