In darts, 170 is the highest possible checkout with three darts.
It is completed with treble 20, treble 20 and the bullseye: 60 + 60 + 50. Because a checkout must finish on a double or the bullseye, the final dart cannot simply be another treble.
The 170 finish is often called the “big fish,” a traditional darts nickname. It is especially notable because it uses the highest-value treble twice before finishing on the board’s 50-point centre.
A score of 180 is higher than 170, but it is not a checkout because three treble 20s leave no dart available to finish the leg. Other high finishes, such as 167 and 161, are possible but score fewer points.