Each circuit in 74LS14 functions as an inverter. However, because of the Schmitt-Trigger action, they have different input threshold levels for positive-going (VT+) and negative-going (VT–) signals. These circuits are temperature compensated and can be triggered from the lowest of input ramps and still give clean, jitter-free output signals.

NOTE: HC version is the high speed CMOS version which we may supply due to availability. It is fully compatible with LS version and one to one replaceable (not vice versa as HC version has more features)

Datasheet:

LS: https://www.ti.com/lit/ds/symlink/sn54ls14-sp.pdf

HC: https://www.ti.com/lit/ds/symlink/sn74hc14.pdf