I recently built an 8'x12' 40 degree wall in my backyard for home training during the pandemic, and grabbed a set of these 21 steep wall feet.
Like many others I also thought these would be pretty small judging by the photos, but was looking to set in the V4-V6 range on the wall anyways so that wasn't a problem. Turns out there's a good variety of sizes in this pack, with about 5 or 6 of them being suitable as (small and difficult) handholds. I've used just about all 21 of them now within a week of the wall being up, and find them to be great for bringing up the difficulty on a problem by swapping in one of these as a handhold.
Overall this is a great pack as a great price, especially if you're looking to increase the difficulty of the wall but don't want to commit to a pack of small crimps or something similar. As feet they all function well, but have ways they can be positioned to once more increase difficulty. Highly recommend for new walls / filling out an existing set.