Firstly, good call on being responsible about size, however, genetics is about 50% of the snakes size, the rest is up to you, a lot of people get retics because they want a monster, so they feed it big meals sometimes twice a week all its life, these snakes will get big!!!! If you feed it a meal NO thicker than the largest part of its body once a week til its 1, then move it to every 10-14 days, a male retic is going to only get 10-15ft, (thats the range is where genetics kick in) males rarely get over 16ft either way and stay quite slender, don't get me wrong these are still powerful snakes and should be shown respect, but i will comfortably handle a male alone (but i am a big guy). Females on the other hand, rarely stay UNDER 16ft, and are very heavy bodied. So what i'm saying here is, don't rule out mainlands, as you can get a lot more variety morph wise for a lot less than dwarfs and super dwarfs.
Secondly, retics have this strange aura around them for being "snappy", well all snakes can be snappy, retics more so? Not really, its just thats its a lot more dangerous when they are because of their size. They do however have a WICKED feeding response, they expect food 24/7 so i suggest hook/touch training them. But most importantly, handle and pay attention to your baby BEFORE you buy it, if it has an attitude as a baby, it is more likely to have one as an adult.
Ok rambling over, onto what you actually want to know D and SD sizes:
Super Dwarf: males 5-8, females 6-9
Dwarfs: males 6-9 females 8-12
Hope i have cleared some extra things for you
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