the 7/8" weaver is talking about the rail. that just means that it will fit on the picatinny rail. afaik, even if they don't specify, all the AR carry handles will fit the picatinny rail... wouldn't make sense if it didn't.

model 4/15... i think you are correct. seems like what UTG calls their parts that will fit the M4 or AR-15 variants. not sure.

if you are talking about UTG version 6, then it just seems like that is their latest version. i don't know what the difference is between it and their earlier versions.

match grade supposedly means it has tighter tolerances and can be used for competition. i have seen that term used both for parts and ammunition.

personally, when i bought my carry handle, i just made sure it came off of a colt. i am sure other brands make good carry handles. i just went with a brand i thought i could trust...

mine is just sitting in my parts box. i don't intend to use it, but just cool to have.