Oven Heat Deflection Kit

Hi All

We recently gathered numerous quotes from B&Q, Wickes, Howdens etc all to include under worktop Oven.

Only B&Q mentioned we need a heat deflector kit
https://www.diy.com/departments/goo...at-deflector-kit-l-895mm/3663602643555_BQ.prd

Were not buying from B&Q but do you experts fit these as standard?

Thanks in advance