A Fastener rivet is a permanent mechanical fastener. Before being installed, a Fastener rivet consists of a smooth cylindrical shaft with a head on one end, and the end opposite to the head is called the tail. On installation, the fastener rivet is placed in a punched or drilled hole, and the tail is upset, or bucked (i.e., deformed), so that it expands to about 1.5 times the original shaft diameter, holding the rivet in place. In other words, the pounding or pulling creates a new "head" on the tail end by smashing the "tail" material flatter, resulting in a Fastener rivet that is roughly a dumbbell shape. To distinguish between the two ends of the fastener rivet, the original head is called the factory head and the deformed end is called the shop head or buck-tail. Rivets come in various grades of steel such as aluminium, steel, and stainless steel. Because there is effectively a head on each end of an installed Fastener rivet, it can support tension loads. However, it is much more capable of supporting shear loads (loads perpendicular to the axis of the shaft). There are several types of rivets, designed to meet different cost, accessibility, and strength requirements. The most common types are Blind rivets, Solid/round head rivets, High-strength structural steel rivets and Semi-tubular rivets.