4 layers of 70% Bamboo viscose and 30% cotton blend inserts.  360 gsm per layer
Will fit Littlest on the second rise and bigger up to the 2nd rise snap on Middlest pockets.  On the 3x2rise versions of Littlest fully snapped it might be hard to leg seal but on middle rise and bigger it will fit nicely. 
It does bacon a smidge but it makes a great booster for pockets and preflats.