I had a big project on my car and needed the car to stay on stands full height for a couple of weeks (winds, rain, etc...), checked all over the net and was not happy of what was available in the market, totally rubbish stuff. I found these from USA to be the safest stands and afordable at the same time.
 
Features that I was looking for:
+ Safty pin, Double locking (most important feature)
+ Flat feet to prevent sinking in the ground (2nd important feature)
+ Known Brand
+ Up to 40cm height
+ 3 Ton (these were 3t a leg)
Project farm on youtube did a test on these monsters and they performed excellent that gave me the confidence to lie down under the car without worrying about a possible accident. I purchased 2 pairs (shown in last pic for reference only) one extra as back up. They were so good and strong that one pair was more than enough.

Brand new never used but packaging was open as shown in photos.

Same day dispatch if ordered before 2.30pm