<http://schema.org/description>
"Ronstan's Stand-up base accepts a 3/8 in. post and 3/16 in. pin. It works with all Ronstan Series 40 blocks with posts (i.e. not loop heads). It also works with single blocks with posts from Ronstan's Series 50. The base is a rhombus and measures 51mm x 75mm (2 in. x 2 31/32 in.) angle-to-angle."^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.apsltd.com/stand-up-base.html>