SharePoint List Read Only

Using OneDrive for Business and SharePoint Online / Microsoft Lists.

I have a simple 'Reserve an Item' list in SharePoint, it contains the following columns (I have removed a lot of columns for this example);

Item List

 - description (text)

 - type (dropdown - book, tablet, laptop)

 - status (drop down - available / on loan)

 - allocated to (lookup)

 - loan date (date time)

I populate this list when an item is loaned to a person.

The description and type columns will never change - so how can I set this to read only as I will never need to edit them, although I do need to see them and I do need for them to be part of the item list.

Thanks