Homedepot has FLEXVOLT 4-5/16 in. Carbide Wood Hole Saw for $6.50 Shipping is free.
DEWALT FLEXVOLT High Efficiency Accessories are engineered to maximize runtime. The hole saws feature a self-feed pilot bit for fast, efficient cutting, carbide teeth for long life, and a thin Kerf design for high efficiency. For use in cordless and corded tools.
https://www.homedepot.c