Connector and connector assembly

A connector assembly, comprising:

• a first connector having:
• a first housing;
• and a plurality of first terminals attached to the first housing and aligned in a first direction;
• and
• a second connector having a second housing and a plurality of second terminals aligned in the first direction;
• wherein the first housing has a peripheral wall part having at an inner side a recessed portion at which the second connector is arranged,
• the peripheral wall part has:
• two wall parts extending in the first direction, and opposing each other in a second direction orthogonal with respect to the first direction;
• and end wall parts positioned at the ends of the two wall parts, and extending in the second direction,
• a through hole penetrating each of the end wall parts in the first direction is formed in each of the end wall parts,
• the first connector has a slider arranged in the through hole,
• the slider can be slid in the first direction between a locked position at which the slider is engaged with the second connector and an unlocked position at which the slider is separated from the second connector when the second connector is arranged inside the peripheral wall part, and
• the slider is a plate-like member arranged such that the thickness direction thereof is oriented to a third direction which is the height direction of the first housing,
• wherein the slider has an operation part that protrudes from the through hole formed in the first housing to the outside in the left-first direction.