The PTFE bush go’s in at a 45 degree’s and there are no moving plastic parts!! Hole is 6mm ….PTFE bush is 3.8mm. The sleeve is very light! The 6mm hole comes already in the sleeve! So it’s just a case of pull down the sleeve till it locks into place! Mark the hole, take in off drill a 6mm hole then slide the wrap over the 6mm hole!.. fit the bush housing by putting it into the hole, then slide the bush into the housing at 45 degrees which locks it all off!! Save yourself 20 quid on a wrap and have a perfect centrally alined elastic!! So simple to fit!