Contemporary L&G tractors will only need a feeler gauge to set the valves cause there's no points no more. Whatever the valve clearance spec is that's the gauge set you need. If you have an older unit with points then you'll need a gauge set that spans those measurements and pay attention to metric and SAE.

I'd think a feeler gauge is easy enough to buy at any auto parts store... even Walmart has them so why buy online?

Thanks justalurker, while my age is not new...my attempts to work on my riding mowers are in the early stages. I was going to order a couple of things for them from Jacks small engine (used them before) and I needed a set to adj the valves on a 20hp ohv briggs and stratton and set the gap on a plug or two. That's when I saw so many different sets. Probably best to go and talk to auto parts clerk like you said. We have one parts store in town but have to drive 20 miles to get to Walmart. Tks again.

For gapping plugs you want round wire gauges and for valves flat gauges.