Various studies have examined condom breakage, which looked, among other things, at penis size as a factor for breakage or slippage. Although the most common type of condom, those made of latex, have great ability to stretch, they are vulnerable to dry friction (i.e., the dry rubbing motion of sexual activity when there is tight pressure or a lack of smooth lubricated movement) as well as other mistakes of usage. In a separate study of people practicing anal sex, condom breakage was linked more to excessive friction (in this case due to low usage of a sexual lubricant) than to penis size.Penis size did not influence slippage, but penis circumference and broken condoms were strongly correlated, with larger sizes increasing the rate of breakage. Men with macrophallism sometimes find it hard to find a condom that fits.