Bracers of Archery

Wondrous Item, Uncommon (Requires Attunement)

While wearing these bracers, you have proficiency with the

Damage: 1d8 Piercing Mastery: Slow
Weight: 2 lb. Cost: 50 GP
Properties: Ammunition (Range 150/600; Arrow), Heavy, Two-Handed

and

Damage: 1d6 Piercing Mastery: Vex
Weight: 2 lb. Cost: 25 GP
Properties: Ammunition (Range 80/320; Arrow), Two-Handed

, and you gain a +2 bonus to damage rolls made with such weapons.

Source: Dungeon Master's Guide, p. 240