This mine is a classroom instruction version of TMM-1. It has no explosive filling, it is used only as a model to train soldiers. The mine has the same dimensions, colour and weight as "live" TMM-1. It was filled with sand, to have the same weight as the original.
It has four holes drilled through the upper part of the mine body, but it is just because it is school model, and the holes were taped shut from the inside to hold up sand from going out if the mine is turned upside down. It also has 2 holes with M10X1 threads for screwing school boobytrap fuzes (pull or preasure-release), these fuze wells are shut with plastic protective caps.