A mine stopping panel and method of making it are disclosed. In one embodiment, the panel includes first and second channel-shaped panel members having a telescoping sliding fit one inside the other. An elongate end cap fitted in the first panel member. One or more connections between the first panel member and the end cap hold the end cap against movement relative to the first panel member when an extending force is applied to the end cap tending to telescopically extend the first panel member relative to the second panel member. At least one device on the end cap is configured for engagement with the first panel member to resist telescopic movement of the first end cap relative to the first panel member when a contracting force is applied to the first end cap. Other improved mechanisms for resisting contracting forces are disclosed.