You can add remarks to each material while adding them to your invoice list

• Go to Sales >> Invoice.
• Click + create.
• Enter the fields.
• Choose the material from the drop down.
• Enter the information in the remark tab.
• Click add +.
• Keep adding material as much you need.

Make sure that remark tab is enabled in invoice template, to enable the option.

• Go to settings >> invoice template.
• Go to item table tab.
• Click the remarks check box.
• Click save.
• You can now view the entered item information in your invoice.