Tooth-like nibs under the head allow the screw to countersink itself- Square X head accepts both square drive and Phillips bits.
Centerline #6 x 1'' Trim Head Square Drive Wood Screws
100 Pack # 8 x 1-1/2 Flat Head Square Drive Wood Screw, Course
CSH #8 x 1-1/2 in. Black Combo Drive Flat-Head Coarse Thread with Nibs Self-Tapping (Set of 1000) 0.FCC08112BN17
specs
Everbilt #8 x 1-1/2 in. Zinc Plated Square Flat Head Wood Screw (5
Rockler Centerline #8 x 1/2'' Low-Profile Washer Head Screws, Deep Thread, Zinc, 100-Pack
#8 Flat Head Square Drive Standard Screws 1 1/2 (Bag
#8 x 1 Flat Head Wood Screws - #2 Philips Drive
Peachtree Woodworking Catalog Pages 51-100 - Flip PDF Download