The Zappu Sasuteki Screw-in weight is a weight that doesn't necessarily screw into the bait but you insert the weight into the rear of the bait and run the hook point through the eye of the Sasuteki Weight.  The Sasuteki weight helps your rig get through the weeds for punching grass. 

This weight works well with these baits:
Jackall Sasuteki Craw
Owner Yuki Bug
Spiky Avalanche
Deps Deathadder Hog