Rings of Gold Poles of Acacia Wood

שמות כה: (יב ) וְיָצַקְתָ לּוֹ אַרְ בַע טַבְעֹת זָהָב וְנָתַתָה עַל אַרְ בַע פַעֲמֹתָיו וּשְתֵּי טַבָעֹת עַל־צַלְעוֹ הָאֶחָת וּשְתֵּי טַבָעֹת עַל־צַלְעוֹ הַשֵּנִית: (יג ) וְעָשִיתָ בַדֵּי עֲצֵּי שִטִים וְצִפִיתָ אֹתָם זָהָב:

The Mizbeach for the Mishkan had rings attached with permanent poles.

A collection of opinions about the rings and poles:

CommentatorRingsPolesNotesRashi42The rings were attached near the top of the Holy Ark.Ramban42The rings were attached close to the bottom.Ibn Ezra82The Holy Ark had legs and four of the rings were attached near the top. The two poles were placed into these rings to enable carrying the Holy Ark. The other four rings were attached to the legs and were only ornamental.Ramban's version of the Ibn Ezra82The Holy Ark had legs and four of the rings were attached near the top and were only ornamental. The other four rings were attached to the legs. The two poles were placed into them to enable carrying the Holy ArkTosfos (Yuma 72)84Four of the rings were attached at the corners and four along the sides. All the rings were used to accompany the four poles. Two of the poles remained permanently in place, as per verse 15, and two were placed into the other four rings when there was a need to transport the Holy Ark. Whether the rings that permanently retained the poles were higher or lower than those that were used when traveling is not known.Bechor Shor82Small rings were attached to the Holy Ark and four others, which were both larger and broader, were attached to those rings. The poles were placed into the larger rings.Rosh82Small rings were attached to the Holy Ark at the corners. Their purpose was to have a grip on the Holy Ark when there was a need to fix it. This allowed for it to be lifted, somewhat like a handle. Another four larger rings were attached on its broad side at the top of the bottom quarter of its height (1/4th way up). They were placed 2 and ½ handbreadths away from the corners. It was into these four rings that the two poles were inserted.Chizkuni82There were 4 small rings soldered to the ark. They served as holding rings for another 4 larger rings into which the staves went. This was done so that when at rest, the staves would not be right against the Holy Ark.Malbim82Four of the rings were attached at the corners, while another four were attached three handbreadths inward, on the walls of the Holy Ark. All the rings were the same size and on each side all were in a row. The two poles were each inserted into four rings. The prohibition of verse 15 is limited to removing each/either of the poles from more than two rings.