Docking Station Dock Lenovo Ultrabase Series 3 THINKPAD X220 X220t X230 X230t | eBay
Lenovo 0B67692 FRU: 04W6846 X220 / X230 Docking Station with DVD-RW | A1 Used Computer Systems – Computer Parts, Repair Services
Security Accessories - Reference Guide - Lenovo Support US
IBM Lenovo ThinkPad X6 UltraBase Docking Station Port Replicator No Accessories | eBay
Picked this X41 up for £35 ($45) though was listed with no HDD or accessories. Turns out C was corrupt but had a recovery partition, and came with a dock too! : r/thinkpad