Cobalt

The person must ensure that nothing impure comes into contact with the rida bearing the Prophet's sandal. Additionally, it is discouraged to wear it in the bathroom or while relieving oneself.

It should not be thrown on the floor, stepped on, or handled carelessly. Instead, it should be carefully placed in its appropriate location.

Imam Shaykh Yusuf Al Nabahani composed a poem in honour of the Prophet's sandal:

Verily I serve the image of the Sandal of Mustafa
That I shall live under its shadow in both worlds
Ibn Masud was in the service of His Sandal
And I am fortunate by serving its image
I dust the Sandal image with the whiteness of my beard
Since the Prophet (peace and blessings be upon him) fastened the band that passed between His toes
It is not for the image that my heart is longing
Yet it yearns for the one who wore this Sandal
We are lowered by awe to honour this Sandal
And whenever we lower before it we are raised
So place it on the highest shelf!
For indeed in reality it is a crown and only outwardly a Sandal

Wallahua'lam