Shape

In terms of shape, the closest thing to the PRIMER is the SteelSeries Rival 310. Much like the latter, the PRIMER has a narrow front, wider back that flares out significantly to the right, and a rather low button height. There are two key differences, however. While the Rival 310 has a pronounced raised left, the PRIMER stays almost flat across the entire width. Furthermore, the hump isn't centered but rather positioned towards the back, which is reminiscent of Zowie's ZA series. In fact, the overall profile of the PRIMER is somewhat low in relation to its overall size. While the shape first felt a bit alien in hand for me, I quickly got used to it and ended up finding it surprisingly comfortable. It's no doubt a unique and fairly original design.


As for grip styles, I'd say the PRIMER is best suited for palm and claw grip simply because of its general size and shape. It's a large mouse with a moderately pronounced hump, which makes it mostly suitable for larger hands. For reference, my hands are 19 cm long and 10 cm wide, and I found the PRIMER comfortable in claw grip.

Dimensions

This table includes the dimensions of the XPG PRIMER and several other right-handed ergonomic mice. "Front height" denotes the distance between the base and main buttons. Measurements with two decimals have been taken with a caliper, while those with one decimal have been taken with a ruler. For a full list of all measurements taken, please refer to this sheet compiled by an esteemed community member.


Here are some comparison shots with each of the measured mice:


SteelSeries Rival 310


Glorious Model D


ROCCAT Kain 100 AIMO