An inexpensive unit-block-like set of sharp-edged pine.
Manufacturer Maxim has replaced this series with identically dimensioned hardwood blocks of mellower color, tighter grain, and partially rounded edges. Now in Maxim's Preschool product line, rather than Tumble Tree, they seem to have the same part numbers!
The 30mm pitch is a very nice size for building, albeit compatible with neither "tabletop" sizes (usually 25mm) nor "kindergarten" size (35mm). The emphasis is on smaller blocks - cubes and double length - rather than the longer blocks of Unit Block sets. There is a passable, simple selection of pieces.
The structure used all the pieces of a 50 piece set.
(I built the structure & took the picture in January, but wrote the text and cleaned up the picture today)