460mL of water
The XP 40 is a 1998 XP Super Soaker that holds 460mL of water. It is the successor to the Super Soaker 30 and XP 35, and is no longer available, having been succeeded by the XP 240 and then Max-D 4000. It is an Air Blaster.
Its major improvement over the XP 35 is that it is refilled via a screw-off cap, rather than needing to detach the entire water tank. It shares this feature with the rest of the third XP generation.