The battery holder is functional, leaves nothing to be desired. Only the insert and remove the batteries requires a little bit of flair. There is nothing to complain about switches and small components - the gear with slipping clutch is very valuable, because the engine is already pretty torquey. If you use more engines, this gear is a must if you want to prevent damage ...
The two enclosed LEDs are a little weak - as a reading lamp etc. probably less suitable.
All in all, this is a set that I highly recommend. When the purchase price but you should look exactly as it varies quite strongly ...