Instant Legolas (5e Equipment)
From D&D Wiki
An "Instant Legolas" resembles a quiver mounted on any sort of bow. This majestic piece of carpeting was invented by the master slingshotter and novice bowman, the human Joerg Sprave. It takes one minute to attach one of these to a bow.
A typical Instant Legolas can hold 4 arrows, but they can only have 2 fins, instead of the normal 3. Anyone using a bow with one of these quivers attached may make an extra attack whenever they take the attack option. However, after firing 4 arrows you need to take the reload action. Additionally, the normal range decreases by 10 feet and the long range by 30.
A popular way to circumvent this is by attaching an Ammo Duplicator inside the quiver. These types, however, can easily cost over 10000 gp.