What is a Seven Dolors rosary?

The Seven Dolors are Mary's Seven Sorrows:

1. The piercing of her heart, foretold at Jesus' presentation in the Temple
2. The flight into Egypt
3. The search for the child Jesus in Jerusalem
4. Meeting Christ on the road to Calvary
5. Standing near the cross
6. Receiving Christ's body from the cross
7. The burial of Christ

How to pray the Rosary of the Seven Sorrows, also called the Servite Rosary because the Order of the Servants of Mary promotes it, is explained on the website of the National Sanctuary of Our Sorrowful Mother in Portland, Oregon (thegrotto.org).