you can usually tell what sizes to use judging by the snake your trying to probe. but if your not 100% on what your doing... don't do it!! you can cause so much damage!! for smaller snakes we tend to use animal urinary catheters (they r flexible and sterile) so perfect!
Well the thing is, there is no one here on Iceland that can do it (you guys let me know if you ever come here :lol: ) so what I have been dooing is I bought some teaching material from a veterinary collega and it has a video and step to step directions on how to probe, but since I can't buy them here and have to order over the internet (if I want to get it that is) and I didn't understand the sizes, I didn't want to order it, the snakes I have are Ball Pythons and Corn Snakes, so numbers made no sense to me :lol: