Turns relay

Received turn signal relay from China, delivery time 3 weeks. Designed for motorcycles and mopeds, but can also be used for cars.
Testing with a conventional and LED lamp showedexcellent work, the frequency varies widely. The description on the site stated 2x21vt + 4vt., Which caused doubt, so I decided to open it and get acquainted with the elements and circuitry.

The device diagram turned out like this

The power element is a Mosfet transistor, from the datasheet I got acquainted with the characteristics and realized that a radiator for a transistor is indispensable.
I decided to connect a load of 20 watts. The result was expected, the transistor began to heat furiously, and through it the entire board. I glued a radiator 10x20mm. Satisfactory heating (50g).
He took for installation on reversing lights.
1.Good, workable goods;
2. To maintain the thermal regime, it is advisable to install a radiator on the output transistor and drill a few holes in the case.