Here is a picture showing the different sizes of the Mad Dads.
From left to right:
MD3 - great jig trailer or rig it for smaller fish t-rig, etc.
MD3SC - same as the MD3 except the claws are slightly wider and have a little more action to them
MD3XL - perfect t-rig, this is my go to craw when the bite is really tough. You can also use it as a jig trailer as is or cut it down
MD4 - Designed as a flipping bait but can also be used as a bigger trailer
MD5XC - Has the MD4 body but the MD5 claws - lots of action
MD5 - This is a big bait. Perfect for targeting trophy fish. Works great on a big jig, t-rig, Carolina rig, etc.
Hopefully this helps.
Let me know if you have any questions.