What is an Insulator (System board misc parts) / Screw Kit?

[ssd_thinkpad]

I am planning to order everything for a motherboard update and saw this item:

System board miscellaneous parts (integrate), FRU 41V9924

• v Insulator, 1
• v Insulator, 2
• v Insulator, 3
• v Insulator, 4

For what can I use these insulators? Thanks.

Another question: The T60 Screw kit (including nylon-coated screws), FRU 41W4504 is not available from ibm store at this time, would you recommend me the Screw kit T61, FRU 42X4676?