Van floor hose 4way roller/ports - DIY

[NoName]

I'm looking to fit a through the van floor 4way rollers/hose port, so I was eyeing up the 'Waterworks HD Security Guides' 

https://waterworkswindowcleaning.co.uk/product/hd-security-guides/  then it occurred to me that this looks a fairly straight forward diy job with only the four below components... 

3x 4way rollers 4way roller guides

2 threaded bars screfix threaded rods

30-40 thread connector nuts Screwfix threaded rod connector nuts

2 Dome nuts Scrfewfix dome nuts

What am I missing - surely this is straight forward build (famous last words) has anyone already sussed this and hit any roadblocks - my finger is hovering over the 'submit order' button...

 

[Pjj]

They are a doddle to fit I have them in all my vans works well , it’s worth investing in a hole saw to get a nice neat hole rather than using a jigsaw , as always measure twise drill once ???