Thumb Screws are available in two distinct styles, each with two variations. Knurled Thumb Screws feature a round head and can be purchased with or without a washer face below the head. Type P thumb Screws similarly come with or without a shoulder just below the head. Knurled style is available in aluminum and stainless steel. Type P is available in steel with a zinc or black oxide finish, and in 18-8 stainless steel.