Cheaper than a sacrificial PT 4x6.Looks like dunnage off a semi truck that you set a load on so you can fork lift it on and off. Low grade hardwood, usually bowed, bent, twisted and possibly seriously stresses. They may be cheap but they are not good for much except dunnage and fire pits. Cribbing maybe if cut short. Never seen them for sale in a box store before.
I did that also but after somewhat short use, the 16" sections between saw cuts split off from rolling logs against them. Sometimes I get a log roll off the front when loading with the forklift. Have to make sure the saw is clear from front and sides when loading deck. For what it is it works pretty good.the only difference being I don't use a 4x6 on the end. I use a 2x10.