Sales fell by 28 percent to $6.7 million in Heelys’ first quarter, ended March 31. The loss improved slightly to $1.2 million from a loss of $1.3 million in 2009. The gross margin was up by 11.2 percentage points to 47.9 percent. Combined cash and investments rose slightly over the three months to $67.9 million, compared with $66.5 million at the end of December. The company is introducing two new products during the summer.