The high cap is 80865-TX9-A01. The low cap is 80866-TX9-A01.
It's likely some shop was doing work on your A/C system, and neglected to replace them. There's no reason to remove them other than during service or disassembly of the A/C system.
They keep dirt out of your A/C system valves, but also help contain the refrigerant once the valves get old and start leaking.
Generic part replacement should be OK.