These 6-inch bar clamps are similar,  but not the same.  The top clamp is a Brink and Cotton No. 30.  The middle is a Stanley Handyman No. H157.  The bottom one is another Stanley H157, without the Handyman stamp. The Handyman tools are often identified by the red and blue painted surfaces. The Handyman series also tends to be lower quality, homeowner oriented tools. They work, but there are better options.  On the other hand, they are also considered collectible.  This was part of the toolbox clean out buy last weekend.

I got a couple of them, never looked that closely at them. Guess I will next time I go to use them.