4200 is the model number of the Roku 3 itself, not the remote. The original Roku 3 came with RC03 remote, a gaming remote, the last Roku 3 came with RC19 Gaming remote.
The R, X or WR suffixes are meaningless, just where it was purchased. R was retail, X was on-line purchases, WR was bought at Walmart. Nowadays R suffix is the Roku, the box, the all the accessories. Where the Roku by itself has the X suffix.
You want a new remote for your Roku 3, get Wifi Voice remote:
Amazon.com: Roku Voice Remote (Official) for Roku Players, Roku TVs and Roku Audio : Electronics
Its not a gaming remote, what makes a remote gaming remote is the A & B keys, which no current remotes have. Only used ones on ebay.