This is the message from lostinube from sasukemaniac found in thread 'SASUKE 31 Obstacle thread'. Use this info to do editing.
1) This is for SASUKEpedia editors: Until noted otherwise, the only name given so far for the 4th obstacle is Tackle タックル. Tackle boxes is more a description of the obstacle.
2) To clarify how the obstacle works, the competitors have to keep pushing until the three boxes are joined and then the parts of the boxes go into the platform. Only once a certain amount of the boxes are inside the competitor can go over the boxes to the next obstacle. You can see the cavity in the platform in the photo here:www.tvguide.or.jp/wp-content/uploads/2015/06/cyokusoubin_20150618_01_09.jpg They don't have to push the entire contraption in. The netting in the first box is there to assist them in getting over the boxes and onto the platform.