The supplier of mine (mail order) was Motormania Performance Centre of Witham, Essex. They were out of stock and got it sent to me by Auto Inparts Ltd of Leighton Buzzard. Inside the box was an instruction leaflet which said:
IMPORTANT
Please read below carefully before fitting the strut brace.
1. Do not slam the bonnet when the strut brace has been fitted. Check the bonnet is not fouled or impaired by the strut brace.
2. The strut braces are designed for racing so we recommend they are fitted by a qualified mechanic or body shop.
3. Fixings are not supplied with any strut braces. We recommend that the qualified mechanic or body shop doing the installation should be able to decide which are the best fixings. In many cases M8 nuts and bolts are adequate but in some extreme cases larger fixings may be required.
Followed by a warranty disclaimer for improper installation! Probably all stems from legal advice about avoiding claims for damages...