The lengths, as measured from the base of the flange to the end of the threaded female end, are:

1.5 inches – Original Secure Cover

2.0 inches – Pictured in Middle

2.77 inches. – Pictured on Right (Only 4 in Stock)

The engagement length for the pin is 0.25 to 0.5 inches.  This means that the measurement from the top of the slab to the top of the threaded barrel of the Vapor Pin(r) for each cover can be:

1.0 to 1.25 inches

1.5 to 1.75 inches

2.27 to 2.52 inches, respectively