Allied Grid-Lock™ Frames for the Brother PR series home embroidery machines are made to fit the 504mm (approx 19.75") Extra Large Arm Spacing.
They work with the following machine models (and possibly others):
Entrepreneur (PR Series, PR-600, PR-600II, PR-620, PR-650, PR650e)
Entrepreneur Pro (PR-1000, PR1000e)
Allied Grid-Lock™ 15cm Round Frame for the Brother PR Series.