Glue Grenade is unlockable equipment which can be used in one of three equipment slots available per trooper. Upon impact enemy Troopers in affected area lose Initiative, essentially allowing yours to execute a few extra moves before the effect wears off. A grenade with no offensive capability, it's useless if you don't have enough troops to take advantage of the situation.
"- And how exactly do we get rid of this bloody glue?
- You can't. No point in looking."