Poorly engineered. This is a plastic anchor for insulation panels, external or internal. SPIT ISO or FISCHER DIPK are the same in principle. In practice, however, this is far worse. The anchor itself is okay, but the nail is a very loose fit, leading to inconsistent expansion of the anchor (see the gaps present in the photos). Also see in the photos the SPIT ISO anchor I ordinarily use- for comparison (orange nail). The SPIT nail is made from a more robust material (GRP) to withstand MORE hammering, it being a much tighter fit and therefore delivering more consistent expansion within the brick. The serrations on the nail also add to the pulling resistance. A much more reliable fixing. This twistfix nail looks like it's simply extruded plastic. The ejection points are so large they stand proud of the nail shank, so it's these that are expanding the anchor, not the nail, rendering the serrations on the nail pointless because they're not even making contact with the anchor! The last thing I want to be doing is doubting whether 50sqm of panels will be sufficiently restrained by this fixing. Made a mistake in thinking these would be an equal to the SPIT fixing because the cost pretty much the same. Delivery was relatively expensive for just 1, light, shoe box sized parcel (£8+) and it took a few working days to arrive. Website was good and email updates about the order were also timely and useful.