These hex keys use Wera's Hex Plus profile which increases contact of the tool with the fastener screw head corners, leading to reduced fastener stripping.
Compared to the Bondhus hex keys we also sell, you'll notice these typically have a longer length. For 3/8 you'll find it about 1.5" longer, 1/4 almost 2" longer, 1/8" about 1" longer. They will fit in our Fireball Tool hex key holders, but they look a little funny because of their extra length.
Sizes are marked in white lettering on gray background for good contrast.