You can use plates of all sizes for this movement as long as you can grip them and hold on long enough to perform it.
Outer portion of your bicep.
A group of muscles on the outside and sides of your lower arm.
Inner portion of your bicep.
A group of muscles on the inside of your lower arm.
Weight Plate
You can use a weight plate of any size as long as you can hold it properly. If you have trouble achieving the desired range of motion, try using a plate of a smaller size.
Exercises that target the same primary muscle groups and require the same equipment.
Exercises that target the same primary muscle groups with different equipment