As I understand, its probably a Tourney TZ as it is sold as "for 7-speed" while the TX as an "8-speed"; the Schwinn Loop is a 7-speed bicycle.
Maybe either will work, as what makes the precise shifting is the shifter mechanism and the hi/low screws are for limiting travel preventing the derailer move past the cogs.
Last edited by Juan el Boricua; 07-31-21 at 10:23 PM.