Komentarz do Wyjścia 26:29

בתים לבריחם FOR PLACES FOR THE BOLTS — The rings which you shall make on them (the boards) shall serve as receptacles into which the bolts shall be inserted.

ואת טבעותיהם, it is customary for bolts to be inserted through rings unless the Torah would explain that it was not so, as in the case of the central bolt which was not fastened to the outside of the boards at all but inside of them as explained in verse 28.

He fastened them near the rings. . . Explanation: the cane sections did not cover the rings, but reached from ring to ring. Therefore, each plank needed one [set of] half canes [above and below], since each plank had two rings.

וצפית את הבריחם זהב AND THOU SHALT OVERLAY THE BOLTS WITH GOLD —This does not mean that the gold should be attached to the bolts for there was no overlay on them, but on the boards there were fixed a kind of two gold staples something like the two longitudinal sections of a hollow cane. These were fixed close to each ring on both sides of it. The length of the two staples filled up the space along the width of the board, one extending from the ring in this direction, the other from it (the ring) again in the other direction. Thus the bolts appeared to be covered with gold when they were lying on the boards. These bolts formed a projection on the walls outside. Thus neither the rings nor the staples were visible within the interior of the Tabernacle, but the entire surface of the wall within was unbroken.