The Teledyne FLIR MRPINS4 4 Inch Pins for MR06, MR07 and MR08 Units (1 Pair) are smaller in diameter - requiring minimal force to drive the pins into a surface - resulting in less impact to the material. The sandblasted, hardened-steel pins with single-piece design prevent bending and create an improved bonding surface for the abrasion-resistant insulation. The insulation extends all the way to the connection to the probe, so even if you drive the pins all the way into the wall cavity, the drywall will not affect the measurement.