The first (and only) set of "Tough-Built" trestles I had were like the ones
@Sheptonphil shows and were great when they were new - but gradually fell apart over about a 12 month period. They contain ridiciulous quantities of screws, nuts and washers, all non-metric (so awkward to replace like for like), which self-loosen and are shed if the trestles are folded up and moved multiple times in a day as you do on site, as well as travelling thousands of miles in the back of a van. After being nagged for spares the importer supplied a big bag of fastenings which I use to rebuild the trestles along with Loctite. It was so good that a further 6 months down the line I skipped them as they were once again shedding fastebibgs and I couldn't be pineappled to waste any more time and effort on a grorified Meccano kit. The other thing about them, those useful looking "hooks", which are meant (according to the original publicity blurb) to hold a couple of pieces of "4 x 2", turned out to be too narrow to hold the 4 x 2 we get in the UK (actualy around 90 x 44mm finished size) and will actually only hold something like 38mm thick (or non-standard) stock.
So as a tradesman's tool they were unreliable and utterly useless. The only good feature was the variable height legs, Their replacements were a pair of
deWalt DE7035 heavy duty trestles which have done 5-1/2 years service, but they are now fearsomely expensive (a pair were £130 when I got mine) which for a site tool is just a bit steep.