Like I posted before, the field where I fly is grass, with lots of bumps and clumps of crabgrass, gopher holes, etc... The stock tailwheel assembly came off around the 10th flight. I think on takeoff(not sure), so I used the DuBro #957 Tailwheel Assembly. It says it's meant for ".90-1.20 sized aircraft." Works like a charm and plows around with no problems like a 4x4.