Measures 15 X 20 inches (38 X 51cm), perforated down the middle so that you can tear it in half if it's too big (= two pieces of 15 X 10 inches each).
If you require smaller pieces, it can be cut with sharp scissors.
Unless you have a major spill (an entire bottle of acid) each sheet will last many months.
When it comes to protecting yourself (and your furniture!) for spilling drops of acid, there are two 'styles' of working.
In many shops, they place some tissue or kitchen towel on the table, to work over, to catch any drips.
Personally, I hold a tissue in my hand (see the videos).
method is to work over an anti-acid mat, made of a special acid-neutralising material. It not only makes any acid spills harmless, but even stops the fumes.
Comment about the picture: for the sake of the photo we used a dummy bottle (no acid), in real life I hope
the user would be wearing protective gloves
We tested this by filling a standard acid refill bottle with an extra-strong solution of acid, and carefully 'fixing' the bottle so that we knew it would leak.
We put the bottle in one of our leak-proof containers along with two circles of hazmat
We then left it in a car so that it bumped about until all the acid leaked out.
When we opened the container, the bottle was empty, the fabric was slightly damp, there was a slight smell of acid - but no signs of actual wet acid.