Commentary for Exodus 25:27

לעמת המסגרת תהיין הטבעת OVER AGAINST THE RIM SHALL THE RINGS BE — inserted in the legs over against the extremities of the border.

לבתים לבדים, as housings for the staves. Whereas I have explained in connection with the rings of the ark that Betzalel had to cast four rings and attach them firmly to the ark, whereas he would insert a second set of rings inside the first ones to support the staves, the Torah here alters its instructions. Here there was no need to make a second set of rings. The rings mentioned here were the ones into which the staves were inserted directly.

לעומת המסגרת, these were attached at the underside of the table but not to the border (מסגרת).