it's some sort of 300 mhz tx/rx pair. they look pretty easy to use but a bit of googling turned up nothing. It'd use one of those cheap tx/rx pairs and encoder/decoder chips like from holtek.
How can we suggest parts that are available on the other side of the world?
The circuit you showed is from over there somewhere and is very, very old so many of its parts are not made anymore.
Lookup Holtek radio pairs in Google.
I'm sure that small radio tx/rx pairs are available in malaysia. for example abacom makes lots of units **broken link removed** but there are a number of similar ones.
Holtek makes encoders/decoders. Though this company is in the USA and re-lable the datasheets, all their products are made in the far east. https://www.rentron.com/PicBasic/RemoteControl.htm there are lots of schematics on that site. I'd be surpised if you couldn't find something in your area.