It would help to know what Glock model is at issue, and whether OEM or aftermarket is of interest.
Glock part SP O1981 is the extended MAGAZINE CATCH (Glock doed not call it a "magazine release") for all pre-Gen4 9mm, .357SIG, .40SW, and .45GAP models.
If your pistol is 10mm or .45ACP of ANY generation, there is NO Glock OEM extended magazine catch made.