Information about the original Bosch Universal Bowl in stainless can be found here: The Original Bosch Universal Bowl.
MUZ6SB3 & MUZ6SB4
L’Equip is making two stainless steel all-purpose bowls for the Bosch Universal mixers: the MUZ6SB3 and the MUZ6SB4. Both bowls will fit either the classic Universals or the Universal Plus. Both come with a removable drive shaft for easy cleaning. Both are 5.5 quart bowls with a dough capacity of 12 pounds.
The difference between the SB3 and SB4 is the number of splash-ring locking pins. The SB3 has three pins that will allow it to use the 3-pin splash-rings of the MUZ6KR4 plastic bowl. The SB4 has four locking pins to match the Universal Plus’ MUZ6KR4UC plastic bowl.
Below is the SB4. Note the white bit of plastic on the splash-ring. It is a lock to keep the splash-ring from moving about while the mixer is running.
Bosch makes the MUZ6ER2 stainless steel all-purpose bowl. It has 4 splash-ring locking pins and a removable drive shaft for easy cleaning. It is a 6.5 quart bowl with a 15 pound dough capacity.