I personally have struggled to find any decent reusable training pants that absorb enough, have a good fit, are good quality and don't cost the earth and so these training pants have been designed by ME with those goals in mind.
Our pull-up training pants are designed to help with the toilet training process. They are made with a PUL waterproof outer layer, several layers of bamboo terry & microfiber to absorb wees, and a cotton lining so your little one can feel wet to help them understand the aim of toilet training. They feature a wide hourglass absorbency zone to give maximum leak protection with a little pocket at the back in case you need to boost them with extra absorbency.
Although they are very absorbent, training pants are designed to catch one wee and then be changed - not to be a substitute for a nappy as they have less absorbency.
SIZE: At this stage, our training pants come in just the one size, but they actually fit quite a wide size/age range due to their soft waist and leg elastics. We've aimed for these to fit a 2-4 year old (10-15kgs) but of course as each child can be such a different shape and size, we'd recommend trying one pair before ordering in bulk. Training pants are non-returnable as they are underwear.
TIPS: Training pants should be worn just like undies with the leg elastics sitting up in the 'undie' line, not around the leg. Turn the training pants inside out to dry after washing - they'll dry much faster that way.
Below is a pic of my slim 4½ year old wearing his Navy Nautical training pants.