Unit Blocks are the American Standard of children's playing blocks.
The full size versions are also known as "kindergarten blocks" and were at one time ubiquitous in American early learning. Recent trends toward "teaching the test" have pushed block play into the corners and storerooms of American kindergartens as children spend their time instead on worksheets and "academics." What a tragedy.
These are T. C. Timber "Table Unit Blocks," and have a pitch of 25mm, rather than standard Unit Blocks' 1 3/8" (35mm). That might not sound like a lot of difference, but it means tabletop blocks have only 36% of the bulk (and weight) of their floor-play brethren.
My play style may often be that of a young child, but my back and leg joints are those of a middle aged man. I mostly need to play on the table, not the floor.
Most of the block sets I talk about here are "architectural blocks" based on cubes, and fractions and multiples developed from cubes. The "unit block" of "unit Blocks" is 1x2x4 of the pitch unit (1 3/8"x2 3/4"x5 1/2" in standard floor blocks). Most sets include "double blocks of 1x2x8 (11" floor) and larger sets at least a few "quad blocks" of 1x2x16 (22"). Building with Unit Blocks is quite a different experience.
[Recommended: A Constructivist Approach to Block Play in Early Childhood by Karyn Wellhousen, Judith Kieff]