5pc: RF2131 UHF High Efficiency RF Amplifier 1.2W 4V-7V Class C & A/B ISM 33cm
These would be useful for extending the range of ISM devices on 868MHz in UK/EU such as wireless microphones, RFID systems and alarms. Also on the 900MHz 33cm ham band in the US. Easily battery powered with a 4V.