Abstract: A mechanical retention apparatus suitable for serving as a leg rest release for a wheelchair is provided. The mechanical retention apparatus includes a first cylindrical housing (306) and a second cylindrical housing (304). The first cylindrical housing (306) has interior threads (413), while the second cylindrical housing (304) has a threaded end (313) that is complementary with the internal threads such that the internal threads and the threaded end can engage to form a nested cylindrical housing assembly (311). A unitary shaft-stem assembly (310) includes a push-button (301), a stem (303), and a shaft (302). The shaft (302) can be perdurably connected to the push-button (301) to prevent separation. An axial length (402) of the nested cylindrical housing assembly (311) can be adjusted by rotating the first cylindrical housing (306) relative to the second cylindrical housing (304).