A new email being sent to developers from Apple is offering them the opportunity to buy a specific, single Apple Watch model -- and, importantly, guarantees shipping by April 28. The company is trying to ensure that developers either actively working on Apple Watch applications or are planning to develop apps for that platform have a test model they can use to confirm and troubleshoot their work. Apple is offering a single variation in the pitch to developers: a Sport model (42mm) with the aluminum casing and a blue sport band.