Jack Nuts/Screw Anchor - Pack of 4 M5 Jacknuts

You need a 9mm drill bitHit them slighty on top to slightly bend an start of the collapse when bolting up and try to stop spinning while tightning up. Remember to drill all the way to the double skin in upvc else they will not collaspe to expand as they will catch on the double skin. So expect to have a hole depth of at least 15mm, by 9mm dia drill bit.They can be a pain to fit, but there is no other choice to use them for upvc windows.This seller also gives you the threaded screw with it M5 40mm. But it is true what others saythe pozi head will mash as it seems again cheap china soft metal. Just wish they where torx headed.These are not cheap at £1 each.One star off as the head mashes and wish they where torx headed and not pozi.

Great product, only small down side to it was no recommendations or instruction as to correct drill size required, I know it's easy to work out but just saves messing about.

Does what you expect and seem well made

delivered on time good price i used these for fixing sash jammers on my double glazed plastic windows and doors does the job well.

Useful. The quality is not the best (1 out of 8 did not fold right).

These did the job, however at the price of £1 each I expected them to be gold plated, should have gone to screwfix.

Total pain, will probably have to go and buy some somewhere else to get the job done.

Wanted to buy more based on how they turn out - can see a lot of bad reviews - but seeing the price double overnight seems might not be worth it - so buyers beware the guys are trying to make as much money as they can - I might update based on how the product turns out to be - but personally not very happy dealing with people who want to make a quick buck - a pound for a single screw and bolt