Destron Fearing officially placed the GPR+ Global Pocket Reader went End-of-Life (EOL) on October 1, 2016.
Depending on your needs the idChamp DX1 reader models may work for you.
Destron Fearing Global Pocket Reader™ Plus (GPR+) and Universal Worldscan™ Reader Plus”
Are now supported on iOS apps: iScanBrowser, iScanBrowser Pro, SerialMagic Keys, Cloud-In-Hand® Mobile Grid.
Scan pet and livestock tags into all iOS apps that accept keyboard entry, for use powerful mobile livestock solutions on iOS & Android.
You can click link for step-by-step connecting of GPR+ or UWSR+ 125kHz and 134.2kHz RFID reader to iPhone, iPad or iPod Touch.