Exercises to break through the 4-pack abs?

I've been working out about a month, I've gained muscle and lost fat. My stomach has become almost flat(the lower still sticks out a bit). My upper abs are well defined and are strong, but lower still feels crappy.

I've been doing many variations of crunches, been doing leg and knee lifts, been working my obliques hard as well. My upper abs are well defined, clear squares.

What do I do to work my lower abs? I read some people said weighted ab exercises, I have no clue how to do those? Can someone please give an example?

I hate feeling like a noob :( any help greatly appreciated.

Edit: Btw I'm 5'11, and 185 lbs(big shoulders, chest, and legs, ****ty abs and arms, will try to get a pic later)

straight out leg raises with weight in ur feet if u can. its tough, but it hits my lower abs good.

basically keep your legs straight wehn u raise them.

works best with dumbbells.. wrap your feet around it

What's your lifting routine like? I had a similar problem as you, and the most common advice was to do more Squats, Deadlifts, and Pullups. I am doing a full body routine now and abs are turning out great.

Cardio
Diet

Than...

Dragon Flags
Declined Crunches
Side Bends
Leg Lifts