The Good
Comes directly labelled with FITC. Although not shown here, likely works well against rat tissue.
The Bad
For those working with human tissue, exhibits minimal cross-reactivity (<5%).
The Bottom Line
If you are in urgent need of an antibody against human CD3 for your experiments and you have access to this anti-rat CD3 (clone G4.18) antibody, it will not work as it does not demonstrate cross-reactivity. You are better off using one of the several anti-human CD3 commercially available antibodies.