This is a light-weight modular conversion ring for a Discus circle to Shot Put, Hammer, Weight Throw Circle.  
 
Using keyed foam mats we cut out the proper size insert to take the 2.5-meter circle to 2.135-meter throwing circle. We use a large laser router to cut a smooth accurate insert to the proper size. The pads lock together to form the insert.  The insert fits snug in the discus circle.  The mats are heavy-duty 3/4  inch thick. The circle is accurate to within .5 diameter due to expansion and contraction of foam.  We get material in 3 different colors and depending on availability the one shipped maybe sky blue, silver/grey or black.
 
0, 90, 180 270, are marked on four segments to give visual to the proper foot placement for turns.  Depending on availability they will be on contrasting segment colors or labeled in contrasting ink. 
 
All Porta-Circle products are shipped directly from the manufacturer in Rochester, NY. All products have a flat rate $22.50 shipping charge per item to anywhere in the continental United States.