This is Coleman Shelton's third season in the league so he'll be a restricted free agent (RFA) in 2022.
The Rams can secure right of first refusal by tendering him.
A first-round tender would count $5.479M against the cap as soon as they make the designation (which must be done before mid-March). If Shelton is offered a contract by another team the Rams could match it, but if they chose not to the Rams get a 1st round pick from the other team. And if no one offers a contract the Rams get Shelton for one year at $5.479M (unless Shelton and the Rams negotiate other terms.)
A second-round tender will carry a cap hit of $3.927M and works like the first-round tender.
Or the Rams can do a right-of-first refusal offer. That's would be a $2.396M cap hit and would allow the Rams to match any offer, but the Rams wouldn't get any compensation if they opted not to match.
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