Rodding point access cover, metal or plastic?

[epsilonGreedy]

I need to finish a 110mm drainage pipe that emerges from the footing blockwork at a 30 degree incline.  At ground level it will be located 2ft away from the house. There are two types of rodding point access cover on the market, an oval aluminium cover and a slightly larger square plastic cover. Which is preferred when the access point will be in the middle of a mowed lawn?

 

My inclination is to buy the smaller metal one and set it in a concrete collar about 250mm across about 1" below ground level to ensure it dodges the rotary blade of a mower. The downside of the smaller metal cover is that it might get lost over time.

 

Metal:

https://www.plastics-express.co.uk/underground-drainage/Underground-Drainage-110mm/110mm-oval-aluminium-rodding-eye-p-pte335?gclid=EAIaIQobChMI8Zjvx_SM5QIVBEPTCh3Kbw7JEAQYASABEgL0AfD_BwE

 

Plastic:

https://www.screwfix.com/p/floplast-d884-upvc-rodding-point-socketed-110mm-black/82622

[Mr Punter]

1 hour ago, epsilonGreedy said:

The downside of the smaller metal cover is that it might get lost over time.

 

 

But you could find it with a metal detector!

[PeterW]

Tend to use the ovals tbh as they look neater.