The Tentacle T3 gives you 2 fully isolated channels for EZO circuits made by Atlas Scientific. Channel 3 is also in the EZO form factor and is perfect to add  RTD Temperature compensation to your isolated channels. An additional 2 channels allow you to connect 5-pin devices by Atlas Scientific that come with a Molex connector. These channels can also be used as generic additional I2C connectors.

Isolation

Channel 1 and 2 are fully isolated. Built in electrical isolation means that sensors won’t interfere with each other and most outside electrical noise that can interfere with readings is reduced.

Stackable

By specification, Raspberry HATs are not stackable (That’s why the Tentacle isn’t allowed to be called a HAT). With the Tentacle T3 however you can stack multiple HATs to your Pi. You can stack multiple T3’s, or stack another, normally not stackable HAT on top of the Tentacle. You can easily stack 2 to get 4 isolated channels and 10 channels in total! If you have a beefy power supply and feel like messing with the pullup resistors on board, you can stack even more.

The Tentacle comes with an M2.5 standoff mounting kit.

You can also stack other HATs (that are not stackable by design). For them, the Tentacle is mostly transparent. The Tentacle doesn’t “occupy” any pins of the Raspberry. It’s connected to 5V, 3.3V, GND, SCL, SDA. The Tentacle adds pullup resistors to the I2C line so you don’t have to care about them.