Amazon.com: TPDL DW31A Battery Adapter for Dyson Type A DC31 DC35 DC34 DC45 Vacuum Cleaner, Adapter Convert for Dewalt 20V Lithium Battery to Dyson Type A 22.2V Battery (Not for Type B) :
Kingsener DC31 (fit type A) Li-ion Vacuum Battery For Dyson DC34 DC35 - BatteryMall.com