The transmitter runs on only 3V whereas most others run on more voltage. This dirt cheap item uses non-adjustable inductors so it is not possible to tweak for higher output. The common TX2B chip is manufactured by HIGHLAND (SHENZHEN) ELECTRONICS CO LTD and by REALTEK SEMICONDUCTOR CORP and others.
Datasheets are available on the web but I don`t remember where now. Here is the circuit at 27 and 49 MHz: