Split shot sinkers have a 'split' in one side that you fit your line into; and then you squeeze the sinker with pliers, closing the split around your line to fix the sinker in that position. 

Split shot sinkers are easy to get on and off the line and so are perfect for those situations when you need a little extra weight. 

For most fishing situations, split shot sinkers will do the job.

Split shot sinkers are very useful when fishing light in streams or estuaries. 

Many anglers also use them when float fishing to balance their floats and hold the bait down where the fish are. 

Too much weight will deaden your lure or bait, making it far less attractive to fish.

Split shot is commonly used with live bait like crickets, nightcrawlers, leeches, and minnows, helping you cast them and keeping them submerged.