Plenary Indulgence Obtainable on the Feast of the Holy Apostles, Peter & Paul

A partial indulgence may be obtained on the Feast of the Holy Apostles, Peter and Paul by the faithful, who devoutly use an article of devotion (crucifix, cross, rosary. scapular or medal) properly blessed by a priest.

But if the article of devotion has been blessed by the Sovereign Pontiff or by any Bishop, the faithful, using it, can also gain a plenary indulgence on the Feast of the Holy Apostles, Peter and Paul, provided they also make a profession of faith according to any legitimate formula. A plenary indulgence remits all temporal punishment due to personal sins.

From Norm 17 of the [1967] Apostolic Constitution The Doctrine of Indulgences. Also Norm 19 of the Enchiridion [1968].

Requirements for a Plenary Indulgence on the Feast of the Holy Apostles

◗ devoutly use an article of devotion (crucifix or cross, rosary. scapular or medal) properly blessed by the Sovereign Pontiff or by any Bishop.
◗ Say one "Our Father" and the "Apostles Creed".
◗ Say one "Our Father" and one "Hail Mary" for the Holy Father’s  intentions (the intentions  designated by the Holy Father each month).
◗ Make a sacramental confession within 20 days.
◗ For a plenary indulgence, be free from all attachment to sin, even  venial sin (or the indulgence is partial, not plenary).

Grant, we pray, O Lord our God, that we may be sustained by the intercession of the blessed Apostles Peter and Paul, that, as through them you gave your Church the foundations of her heavenly office, so through them you may help her to eternal salvation. Through our Lord Jesus Christ, your Son, who lives and reigns with you in the unity of the Holy Spirit, one God, for ever and ever. Amen.