This bit has a narrow recessed section, or waist, called the Flex Zone.
This works on the torsion stick principle and will absorb sudden peaks in torque overload, thereby increasing the working life of the bit. The zone is sectioned for maximum durability.
Tin the abbreviation for Titanium Nitride.
This coating has a hardness in the range of 2800HV, which is three times the hardness of an extra hard, uncoated bit.

No.2 Point Pozidriv x 25mm Long
1/4in Hex Drive