The Miyota 8215 and ETA 2824-2 movements are reliable and precise, which are used by some Swiss made replica watch makers world wide. What’s more, they have been produced for years.
Nowadays most watch manufacturers don’t produce their own movements. Some of them now employ "ebauche" (spec) movements, manufactured by ETA, Valjoux and a few others.
Invicta 9937 uses the Swiss ETA 2824-2 25 Jewel Automatic movement.
Some famous watch brands, such as Auguste Reymond, Cartier, Dugena, Eterna, Festina, Fortis, Gaddy’s, Kienzle, Maurice Lacroix, MHR Motochron, Oris, Schwarz-Etienne, Tag Heuer, Tissot and so on, use the Swiss ETA 2824-2 movement.
Camel, Citizen, Dugena, Festina and Invicta use the Miyota 8215 movemnet.
These two movements are similar and different in functionality and application.
Cost – You can pay about $78 for buying a 25 jewel ETA 2824-2 Automatic movement from Ofrei. If you buy a Rolex watch that equipped with this type of movement, it usually cost you thousands dollars. The 21 Jewel Miyota 8215 costs about $37 and is used in watches priced from $100 and up.
BPH – Beats per hour. ETA 2824-2 movement beats 28,800 BPH, while the Miyota 8215 movement beats 21,600 BPH. Accuracy of a watch usually depends on the BPH of a movement, the higher BPH will be more accurate. There is an easy way to judge the quality of a movement. If the second hand runs smoothly, the movement has high quality.
Finish – The Miyota is rougher and less polished than the ETA.
Jewels – The value of jewels is to reduce friction and wear on moving parts. The ETA has 25 jewels and the Miyota has 21 jewels.
Power Reserve – Power reserve is the number of hours a movement will run when fully wound. The ETA has about a 40 hours power reserve, while the Miyota has a 45 hour reserve.
Winding Mechanism – The Miyota employs a ball bearing unidirectional winding rotor. The ETA utilizes a ball bearing rotor that winds in both directions.
Second Hand Drive – The Miyota uses an indirect second hand drive and the ETA uses the newer direct second hand drive.
Shock Resistance – The ETA employs Incabloc shock resistance, while the Miyota uses its own proprietary shock resistance on the balance.
Hacking – When you pull out the crown to set the time, the ETA second hand will stop. The Miyota 8215’s second hand does not stop when setting the time.
Date set – Both of these two movements have the quick set date function.
The ETA 2824-2 movement is better than the Miyota 8215 in my own view. It is made in Swiss and has been created for more than 20 years. Compared with the above technical data, we can see that the 2824-2 movement comes out ahead.