I wonder how old they are?
They look around 4 or 5 months old. You can tell by looking at their teeth.
If they still have their milk teeth (some or all), they are between 4 to 6 months old. Most puppies start losing their baby teeth at around 4 months and have their full set of adult teeth by about 6 months. The front baby teeth start to fall out first, if I'm not mistaken, so if the pups have adult teeth in front, they are probably close to 6 months old. Your vet should be able to give you a good estimate of their age.
BTW, dogs generally reach their full height at around 9 to 12 months, but continue filling out and maturing for up to 2 years (depending on breed type/size). If these pups are closer to or over 6 months, then they will not be as big as the size of their paws might lead you to believe. However, their faces still have a baby look to them, so my guess, based only on that one photo, is that they are 6 months or under.