The 62302 ZZ/2RS bearing you described is a deep groove ball bearing with a 15mm inner diameter, a 42mm outer diameter, and a 17mm width. It is open on both sides, meaning that it does not have any seals or shields to protect the bearing from contaminants. The "ZZ" and "2RS" designations refer to the types of seals or shields that the bearing may have. The "ZZ" designation indicates that the bearing has two metal shields, while the "2RS" designation indicates that it has two rubber seals. This bearing is designed to have high stability and precision, and it may be suitable for use in high-speed or high-load applications.