What is a wooden swing set called that is not an a-frame?

I would like to build my 1 year old twins a simple wooden swingset however I was thinking of doing something different than the traditional a-frame design. Does anyone know what a swingset is called that only has two 4X4's or 6X6's in concrete and than one across the top to hold the swings? Also does anyone know anything about this type of swing or sites that have info. Thanks|||consider using galvanized steel posts such as with large chain link fences, that way when your grand children swing on it the thing won't crack off and hurt them, rather it will last 100 years or untill someone gets rid of it with a reciprocating saw.|||kkkllslkshfdjddkkkkkkkdsngn gkdkddgbdsgk;;gn gldgfgbdilda|||A wooden swing, w/o an a frame, sold at Home Depot!