To increase the difficulty of the movement, hold the plate overhead instead of directly over your chest.
Upper abdomen, from just above your belly button to your sternum. The upper half of the six pack abs.
Lower abdomen, from just above your belly button to your pubis. The lower half of the six pack abs.
Outer sides of your abdomen.
Decline Bench Without Rack
If you can't find this bench, consider using a decline bench with rack instead. If your exercise requires you to use a barbell or bar, you cannot substitute. If you do not need to use either, you probably can substitute.
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