"Progressive springs basically compress harder the tighter they get, where the normal springs have a linear compression resistance.  The only heavy duty ones I could find came in the set.  Each color is a different strength.  I used…"

"Hey Alan, the new pics of your bot look awesome.  I had the same problem as you did when I made my 6 wheeled rover (Richard).  The first time I gave it throttle, it bottomed out and stayed that way until I picked it up.  I ended up…"