🔍 Key Concepts

• Match the head shape of the fastener to the shape of the recess in figure "C" of GS-0015 • Understand the difference between a countersunk hole and a counterbored hole • Recognize which fastener heads are designed to sit flush with the surface

💭 Think About

• Look closely at the side view of figure "C" in GS-0015: what is the shape of the enlarged portion at the top of the hole? Cylindrical or angled? • Among choices A, F, K, and D in GS-0080, which fastener has a head shape that would nest neatly into that angled or straight recess so the top of the head aligns with the surface? • Which of the four choices is clearly not intended to use a nut or a flat washer under the head, but instead fits directly into the shaped recess?

✅ Before You Answer

• Identify whether figure "C" shows a conical (countersink) or flat-bottom (counterbore) enlargement • Verify which choice has a matching underside profile to that recess (flat vs angled underside) • Confirm that your selected fastener, when installed, would sit flush with the top surface shown in GS-0015 figure "C"