"I bought these to join self-assembly units made of 18mm boards, as the metal inter-screws (65152) were not available for immediate store collection. They work well, but they are only just long enough to join these boards (i.e. 36mm total). They will not join up to 42mm as advertised. I have measured them fully closed: they will not close to less than 29mm. So, THE SPECIFICATION SHOULD READ 29-36mm NOT 28-42mm (which presumably applies to cat. 65152). Screwfix, please correct the catalogue entry. Note too that the screw is 6mm but the holes need to be drilled to 8mm to accommodate the plastic ends. The plastic ends stick out about 3mm. Reliability based on using 5 screws which seem to work OK."