Click here for Wookieepedia's article on the Canon version of this subject.  This article covers the Legends version of this subject. 

OnALegendsArticleGoToCanon

Micro-grenades were miniaturized grenades that were fired from micro-grenade launchers, such as the Model MGL-1. The grenades were smaller and less powerful than standard thrown grenades, however they did have the same basic function as their standard counterparts. For example, a micro fragmentation grenade dealt exploding shrapnel damage, a micro stun grenade would deliver non-lethal stun damage, and a micro ion grenade would deliver ionization damage to disable droids.

Micro-grenades generally had a blast radius of approximately 3 meters.

Sources