ConFlex™ Block Filler is a commercial strength acrylic block filler that provides a great foundation for most interior and exterior precast concrete, concrete block, and cinder block substrates. Its acrylic latex formula features enhanced filling qualities so you can apply it with confidence - even over spalled and deteriorated concrete surfaces. In addition to its exceptional filling characteristics, ConFlex Block Filler also helps deliver a smooth uniform finish with great hiding. When the project demands a commercial strength filler, trust ConFlex Block Filler to provide a smooth, attractive foundation and great results. Commercial strength acrylic block filler with excellent filling properties Acrylic latex formulation that applies by brush, roller or spray.