The round 25cm center is offered in two options. The 4 layer center is a standard feature with each target and offers a cheap alternative for recurve and traditional bow shooters.
Of course you can upgrade your 4 layer center to the new improved 6 layer center that include an additional 3 layers of high density, penetration resistant EVA. Measuring a true 28cm in thickness, these centers are designed for greater longevity and cater particularly well to compound shooters and are designed to catch arrows from compound bows up to 60lb
Both the 4 layer and the 6 layer centers are readily available as replacements when the need requires.