X chocks like these that goes between the wheels?
On a slope?
I would not bet my life on those things to hold any trailer on anything more than a very gradual slope..
Yeah, I know, there are folks totally devoted to these things and will risk life and limb and defend them til their deathbead..
They are not real wheel chocks and anyone who says they are , perhaps they can point out how many truckers use them? Those things will never pass the sniff test of any OSHA safety person as wheel chocks.
They depend on your tires staying in place, not moving, not shrinking.. In reality, tires move around when you walk in the trailer which can dislodge x Chocks, tires shrink as the lose air pressure.. So, you have to keep snugging them checking them to make sure they have not shifted and you must keep putting air into the tires to keep them in place..
They have a habit of popping out if you don't bother checking them once and a while or if you set them when tires and air temps or hot and didn't bother to recheck them later.
Tires naturally lose pressure, 1 lb-2 lbs per month, tire pressure goes up and down with air and tire temps..
They are designed to reduce wheel rocking while camping that gives you a forward/backward motion in the trailer, you should ALWAYS use REAL wheel chocks in conjunction with X chocks..
Even the cheap yellow chocks are far more reliable on sloping ground..
About $9 per pair..
For concrete/asphalt surface, get the heavy duty rubber versions which are more like the ones required by OSHA for truckers to use..
Pricey? Yep at $35/pair, but how much is your life worth? How about Your families life? Neighbors life?