I wouldn't trust it.

You can get a 4-1 tree from a reputable nursery on a dwarf rootstock. Don't settle for home depot.

Hi, I agree, I wouldn't trust it either. I bought a combo 4x1 pear from Raintree three years ago. It will finally (I hope produce some pears this year). I don't mean to sound 'anti- big box stores' but when it comes to good grafting (hopefully) and rootstock that you are certain of I would steer clear of your ten to forty foot tree. My combo European pear is from Raintree. They are more expensive, but what I have learned from ordering over the internet, you get what you pay for (sometimes you're surprised with something better!) The rootstock on my combo pear is quince; a dwarfing rootstock. It is doing very well and all five different varieties have taken. I keep it pruned to 8 feet tall. Mrs. G