Why are there only three sizes without an M size for the stainless perforated colander?

The stainless perforated colanders prepared in 3 sizes consist only of XS, S, and L, and the medium size, M, is not produced^[1]. KOINU - Homma Manufacturing explains this solely as being due to manufacturing process reasons^[2]. For those looking for colanders to stack and use with trays, the fact that the medium size is missing may be disappointing.

Made of 0.6mm-thick sheet metal, this colander is divided into three sizes: XS (width 17.2cm, height 21.4cm, height 2.5cm), S (width 20.4cm, height 25.4cm, height 3.2cm), and L (width 23cm, height 29.8cm, height 3.5cm)^[3]. These dimensions are designed to fit snugly inside the standard rectangular prep trays in XS, S, and L sizes from the same brand^[4]. If you want to put together a cooking set to catch frying oil or drain water from vegetables with the colander, you should also choose trays from among XS, S, and L, avoiding M, so you can use them without slipping out of fit^[5].

Generally, perforated molding, which punches dense holes all over a thin stainless steel plate and folds up the edges, is prone to warping at certain ratios due to mold pressure or material tensile strength limits. For sizes where it is difficult to maintain the desired shape and flatness, the production yield can drop sharply. hmmm, the missing M size is close to a decision to avoid forced production in order to maintain a uniform build.