This 31” BEST lightweight stretcher bar is constructed from sustainable white pine. A great option for artists who need a budget friendly option for stretcher bars. Excellent for classroom instruction, art students, teachers, and for any purpose where you need several smaller sized canvases. They should not be used for large paintings; you will need heavy duty stretcher bars for these paintings. The white pine used for these stretcher bars is durable and will last for a long time with proper care. Good for experienced artists as well who need cost effective stretcher bars for their smaller sized works of art.