U.S. patent application 20190168091 (applicant Robert Marc Goldberg, Fayetteville, N.Y.):
"A sports device configured to generate thermal energy to warm surfaces. In one implementation, the sports device embodies a lacrosse stick with a shaft and head. The shaft includes a thermal core with a phase change material that can retain and dissipate heat over an extended period of time. ... Suitable materials may maximize energy storage per unit volume/mass so as to add little weight to the lacrosse stick but still maintain surfaces at temperatures for extended periods. This feature can make the lacrosse stick comfortable for the player to grasp and to handle during game play and practice."