The LP Blast Blocks are a set of percussive instruments that are unique as I haven't seen any other ones than these.  The set comes with both a large and small version of the instrument (or one of the other depending on where you get these) and is supposed to be used like a wood block.  While it does have a somewhat similar sound to a wood block, it is definitely a different instrument and will work better in some situations than in others.  I don't find myself using these all that often, but they do come in handy sometimes in specific situations and for certain types of music like jazz and latin music.  The LP Blast Blocks are made out of plastic and they do seem to be rather cheaply made, which is rare for LP instruments as they usually have pretty sturdy instruments, but I guess that is the nature of this type of percussion instrument.  I have only used these for recording but of course they can be used for live shows as well.  As far as recording goes, usually a Shure SM57 will pick up the sound quite well and I've never tried anything else as this always seems to do the trick.  LP is the best when it comes to percussion and while this isn't close to one of my favorites that they have to offer, it is a unique sound that is hard to replicate with other percussion instruments.  The price isn't expensive, but I do think that they could be a bit cheaper because the do feel cheap and I do worry about breaking them.  If you want to add a unqiue sound to your percussion collection, these are pretty cool but I would start out with some more traditional percussion instruments if you don't already have them.