Glaser Safety Slug

[1][2] To improve ballistic performance, a polymer-tipped round ball was introduced in 1987, and the current compressed core form was first sold in 1988.

The light weight and fragility of the projectile make it unsuitable for open field long-range firing or against heavily guarded targets.

[2] The bullet design can produce deep wounds[4] while failing to pass through structural barriers thicker than drywall or sheet metal.

[5][6] These qualities make it less likely to strike unintended targets (IE: bystanders in another room etc) during indoor combat.

Also, when it strikes a hard surface from which a solid bullet would glance off, it fragments into tiny light pieces, creating less ricochet danger.