They are linear-taper digital potentiometers perform the same function as a mechanical potentiometer or a variable resistor.
MAX5160 Digital Potentiometers - Maxim
Three resistance values are available for each part type: 50kΩ,100kΩ, and 200kΩ. A nominal resistor temperature coefficient of 50ppm/°C end-to-end and only 5ppm/°C ratiometric.
This has 32 Tap Positions, 400Ω Wiper Resistance, 3-Wire Serial Data Input . Power-On Reset: Wiper Goes to Midscale (position 16).
See an application circuit of this chip - A solid-state industrial potentiometer simulates an equivalent mechanical potentiometer, and fits in the same space.
Industrial 0V to +10V Digital Potentiometer
The key to this circuit is a low-power digital potentiometer IC, 100kΩ version (U3). Configured as a voltage divider, this IC provides an output of 32 discrete voltage steps between its minimum and maximum settings (0V and 5V). A low-power linear regulator (U1) provides a +5V supply rail for U2, U3, and a resistor ladder internal to U3 (whose maximum rating is +5V).