Abstract: A collapsible shelter/tent, such as for example an umbrella tent, has a collapsible frame with a plurality of legs that are erected by manually moving two devises toward one another. The shelter/tent includes an improved locking mechanism that very securely maintains the structure in an erected position. The improved locking mechanism includes a generally vertical pin extending from one of the devises that is received inside a socket supported on the other of said clevises. The socket has an engaging member therein that can engage a groove in the generally vertical pin after said generally vertical pin has been inserted into said socket. Preferably, the engaging member is spring biased into the groove. The shelter/tent also includes a variety of novel frame structures. An erection device for erecting a collapsible tent is also included. The erection device includes an elongated pole and a slide member that can be used to control relative movement of the devises toward and away from one another.