Please explain: what is a monstrance?

What is a Monstrance? | The Significance of Eucharistic Adoration

What is a Monstrance? | Trojan Catholic

Largest monstrance in the world

World-Record Monstrance in Louisiana

World-Record Monstrance Crosses Mississippi River For Eucharistic Procession

Pope Leo Blesses with the Eucharist in the Monstrance | Eucharistic Benediction on Corpus Christi